How Did Monogamy Become Normal?

Belinda Tobin
The Moral Dilemma of Monogamy
21 min readJan 27


I must preface this chapter by stating I am not an anthropologist or historian. Moreover, the information contained within is only the tip of the iceberg that is the history of our intimate human relationships. Of course, this circumstance will become apparent as you continue. Still, I decided to provide the disclaimer now rather than risk your disappointment at the end. However, the purpose of this chapter is not to provide a microscopic and accurate history of monogamy. Instead, it is to show how the morality surrounding monogamy has changed over time and set the context for where we find ourselves today. This chapter is all about provoking thought rather than submitting a perfect thesis.

We have seen that monogamy is not ingrained in human physiology, nor is it a behavioural imperative under the natural laws of the universe. Yet, in western cultures, there is a monomania around monogamy. This one relationship idea has been determined as more valuable than any other. Monogamy has been crowned as the moral superior of relationship models. So while it can be argued monogamy is not natural, it is normal for adults to seek a partner and enter a sexually exclusive relationship with them. Here, normal is defined as

“that which is considered usual, typical, or routine.”[1]

However, the law of vibration has been incredibly active throughout the ages. There has been an incredible amount of flux in the rules and feelings around fidelity. If you dig into history, it is clear that the presumption of sexual exclusivity within a couple is a relatively modern arrangement.

The Ancient and Middle Ages

In ancient civilisations, the marital home was expected to portray the height of purity and civility. Sex among the married couple was geared towards reproduction, with lust, love or passion believed to pollute the wholesomeness of the union. Yet it was understood that sexual passion was a natural state that, if suppressed, would create dangerous instability in society. So while procreation was expected only within the marriage, extra-marital sexual exploits for men were expected and accepted and even supported by the state. This division between the purity of the pair and the passion endorsed outside the marriage is represented by the views of the philosopher Seneca:

“Nothing is more impure than to love one’s wife as if she were a mistress.”[2]

Men in Ancient Greece and Rome were provided with several ways to alleviate their desire for sexual variety, including with slaves, Hetarias and concubines. The open availability of sexual and sensual supplements to their wives meant that the males in these cultures were very ‘comfortably polygamous’[3]. It also meant that the stock of potential wives was kept pure for those unmarried men. The men could fulfil their sexual desires without sullying the purity of women who would one day be another man’s husband.

With the prominence of Christianity, the seventh commandment– though shall not commit adultery — became the ruling order. And so, while prostitution was accepted as a necessary evil, married men were technically not allowed to use their services. However, how strongly this commandment has been enforced across the centuries is questionable, certainly where wealth was involved. Charlemagne was crowned the Holy Roman Emperor in 800 by the pope but was well known to demonstrate little “Christian piety in his sexual or marital behaviour.”[4] In the twelfth and thirteenth centuries, adultery was openly advocated as the “highest form of love in the aristocracy.” If you were wealthy and were not having affairs, then there was just not enough love in your life. How incredibly opposite this view is to our modern insular view of devotion!

In the middle ages, similar to the situation in ancient cultures, sex with a spouse was a function of procreation, and passion was to be found in the arms of other lovers. It was unusual for men to have sexual encounters with their wives after the childrearing was complete. Clergy were also embroiled in corruption of the Christian commandments, with many being married and having mistresses. For example, Pope Alexander VI, who ruled the Catholic Church in the late 1400s, had several mistresses during his reign. However, historical records show that he confessed on his deathbed and was surely forgiven for his sins!

The hypocrisy of those in religious power was a motivating force behind the Reformation and the establishment of Protestantism. The other was Henry VIIIs shifting sentiments towards his wives and Anne Boleyn’s insistence that she would not have sex with him until they were married. In this case, a whole religion was created to support new rules around intimate unions that were advantageous to the King. During the Reformation, new words appeared that heralded a greater concern for individual wellbeing over societal stability. Terms such as self-regard, self-love and selfness[5] are, as we will see shortly, the predecessors to self-esteem that contribute to monogamy’s continuing escalation of importance.

While non-monogamy was normal, it is fair to say that it was the right of the rich. Concubines, mistresses and masters were a status symbol that indicated wealth, not only in monetary form but also in the availability of leisure time. Keeping courtesans could be expensive. There were gifts to give and attention required to retain their favour. It is hard to imagine the peasants working at the piggeries having the resources to flitter away on infidelity. Aristocracy also had another important resource: its relationship with the Church. Their financial support of the Church ensured God’s representatives granted them favours and forgiveness.

And of course, it can be asserted that non-monogamy was also normal for men but rare for women. While there are records describing powerful women taking lovers, their pivotal role in providing heirs meant they were more likely to be controlled and chained up with chastity belts[6] rather than allowed courtesans. Most famously, Guinevere paid the ultimate price for her pursuit of love outside her marriage to Arthur, and Anne Boleyn was beheaded based on accusations of adultery.

Right up until the late 1700s, love was seen to be such a fickle emotion that to marry under the influence of it was viewed as stupid and was grounds for banishment and withdrawal of inheritance[7]. Marriage was not used as a public display of devotion but was predominantly a tool for economic advancement. For the upper class, marriage served a political and social function, forming alliances and combining assets to grow the influence and wealth of both parties. Reproduction ensured the continued reign of their dynasty and the opportunity to make further advantageous allegiances through their children. For the poorer classes, marriage was more of a mechanism for survival. Men and women needed the support of each other to till fields and run the trade and artisan businesses that provided their income. Procreation was essential to provide business labour and assist the ageing couple. In this way, regardless of stature, marriage was a function of logic and pragmatism, not of love and passion. These latter pleasures were to be found outside of marriage or not had at all.

The shift towards monogamy

So what changed? When did society begin to focus on the sexual exclusivity of the (married) couple? When did monogamy become the gold standard of morality?

To go through all the events in this evolution would easily fill several books and distract from the intention of this chapter. To keep it simple, I will focus on the three key societal changes that have shaped the current expectations of monogamy. These three influences are:

  1. The joining of love and marriage in the Age of Romanticism (late 18th through to the end of the 19th century)
  2. The rise of Industrialism and the prominence of private property (late 19th century)
  3. The transition from tribes to an insular family unit (20th century onwards).

Love and marriage

In many ways, the Age of Romanticism was a rebellion against its predecessor, the Age of Enlightenment. During the Enlightenment, people sought understanding through science and pursued knowledge through rational reasoning. Newton and Bacon were the heroes of the Enlightenment, and Descartes summed up the times when he said, “I think therefore I am”. As we have seen, humans are far from rational creatures, with emotions driving our behaviour. The Age of Romanticism then sought to shift the balance back towards appreciating and expressing human emotions. Just as the Age of Enlightenment placed extreme faith in science and logic, the Age of Romanticism pushed the pendulum back towards the primacy of our feelings. Where Descartes prioritised thought, Lord Byron declared that “the great object of life is sensation.” [8]

In this era, we see a marriage’s politics and practicalities intertwined with and finally overtaken by the notions of love. In the Age of Enlightenment, an institution as pivotal as marriage would never have been left to something as erratic as human emotion. But in Romanticism, pragmatics began to take second place to the importance of passion and sensual pleasure, and the longings of the heart gained prominence over hard-headed intellect. Partnerships were to be predicated on love. The poetry of Byron and Shelley and the Bronte novels are bold examples of the sentiment of the time. Byron describes his lover as walking in beauty, Shelley describes love as a “rapturous thrill”, and in Jane Eyre, the novel’s namesake refuses marriage on the basis of the potential groom’s lack of passion. In Pride and Prejudice, published in 1813, one of literature’s great heroines, Elizabeth Bennet, declares that

“I am determined that only the deepest love will induce me into matrimony.”

Just a few centuries before, in the Enlightenment, it was deemed idiotic to marry for love. The woes of Romeo and Juliet, and Lorenzo and Jessica, written under Shakespeare’s adept hand, bear witness to the lack of regard for love in decisions of wedlock. However, under Romanticism, it was the height of lunacy to consider entering a relationship without it. As a result, love, which was previously pursued outside the marriage, was best found within. Love was not a nice extra to marriage, it became essential.

Passionate sex was previously associated with love (yes, the Sex Trap is centuries old) but was meant to be found outside the constant and calm coupledom. Now though, this love was to be brought within the marriage, and the expectations around sex came with it. Instead of having different homes for the opposing needs of stability and passion, all man’s desires were now to be found within the family, united under the umbrella of love. This transition is displayed in the diagram below.

And this is where we see the very first use of the word monogamous. While the noun monogamy was in use from the 1600s, the adjective of being monogamous only appeared in 1770. With the Age of Romanticism, sexual exclusivity began to be used as an attribute by which people described themselves, and which could be used to distinguish themselves from others. Now people could be classified and criticised for this item of identity.

However, when marriages became predicated on love, sex became a demonstration of love and therefore restricted to those who loved each other. With love embedded into the notion of marriage, then fidelity became evidence of true love. The flow of logic can be read as a set of mathematical equations as follows:

· Passionate sex = love (this came first)

· Marriage = love

· Therefore, marriage now = passionate sex.

Given love was now essential to coupledom, then fidelity also became non-negotiable. It became unacceptable to stray as adultery became an indicator that you no longer loved your partner. And if there was no longer love, there was no reason to stay together. Divorce was very well accepted at this time (thanks to Henry VIII). Hence, the solution to lost love was to divorce and seek revived passion in a new marriage. Does this sound familiar?

I find it astounding that one simple change in the association between marriage and love could have such a profound and persistent effect on mature adult relationships. And yet, it should come as no surprise, for we have heard in the Law of Mentalism that our lives are mental constructs, and our beliefs shape our reality. Nevertheless, it is fascinating that this belief is only two hundred years old and that loving your spouse is a relatively new addition to the relationship rule book.

The rise of private property

At the same time that love was at the forefront of relationships, the Industrial Revolution was in full swing bringing a new wave of equality and egalitarianism to society. With industrialisation, men could find work in factories and gain access to a regular income. This income could finance a wife and family, as well as purchase assets such as property. Now that more men could afford wives, governments had to make sure they could all have access to one. So monogamy was a way to ensure equal access to wives and, by proxy sexual satisfaction and social stability.

Additionally, with regular incomes, more people could save and purchase property and other physical assets. The more you have though, the more you have to protect. It had always been imperative that there was a clear line of inheritance to property and power. Still, instead of being a concern only for the wealthy, the purity of heirs became a consideration for the middle class. And as we have seen, monogamy is a critical mechanism for the maintenance of pure lines of succession and for preventing hard-earned assets from being lost to illegitimate children[10]. No man wanted to pass wealth onto a child that was not his, so having a monogamous wife was imperative. Similarly, each woman wanted to ensure that the assets set aside for their offspring were not ‘stolen’ by illegitimate children. Women then also had a vested interest in deterring infidelity. Marriage was now not only a container for love but a business relationship and a protector of possessions.

In this context, adultery was seen as a sign of lovelessness and as theft of assets. Both man and wife were responsible for creating heirs that would care for the complete stock of family possessions. When one strayed and created children outside this bond, then claims could be made which splintered their hard-earned wealth and sacrificed it to ‘outsiders’. This was equivalent to destroying the couple’s property and stealing from the valid beneficiaries. For these reasons, adultery became a crime in many western nations and is still punishable in several US states.

To see the powerful effect private property had on the ascendency of monogamy, let’s consider a culture with none. This was the case in Ancient Sparta[11]. Here, all resources were held by the city for communal use. Women were treated with a high degree of equality, and even the children were viewed as offspring of the entire community, not just ‘owned’ by their birth parents. Wives were not seen as reproductive property and were free to roam and procreate with other men. This was sometimes encouraged in the name of eugenics and to build a strong, healthy and sustainable society. Adultery was not a concept that even existed, as there was no personal wealth to hang on to or hand down to others. Similarly, there was nothing to be lost in physical possessions or intangible reputation. So what if your wife or husband slept around? You would still be fed, clothed, and have a purposeful existence, and so would your children. Monogamy did not have to be enforced because there was no personal property, or ego, to protect.

The move to an insular family unit

The combination of The Age of Romanticism and Industrialism created a very peculiar outcome, best shown by Maslow’s hierarchy of needs. Industrialism lifted the living standards of many western nations and provided the means to attain private property. As the need for safety was increasingly satisfied, people were free to seek intimacy and connection. People could turn their attention to finding love and building a family (love and belonging) and raise their reputation as upstanding and credible citizens (esteem).

Esteem is now the key focus for many. As a result, all things that came before self-esteem have been transformed into tools to boost an individual’s sense of identity and standing in society. The job, physical possessions and fitness of an individual are all used as status symbols to signify success. Similarly, the person’s family becomes a possession and a resource that can be used to reinforce individual status. A healthy brood of children becomes a testament to the individual’s fertility and virility. And thanks to the link between love and fidelity, a faithful partner indicates the presence of love and, even more importantly, validates the person’s worthiness to be loved. With a preoccupation on Esteem, a cheating spouse becomes the ultimate shame, for it suggests that you are in some way deficient and destroys your public profile.

A person’s sense of worth and self-esteem quickly has now become associated with what they own. The notion of communal resources went out the window long ago as everyone worked to get their own house, car and white picket fence. And then, when they got it, they had to work even harder to get the new model that the Jones’ had just brought home. Materialism thrust society into competition, and this had a dramatic effect on the expectations of coupledom. No longer do the couple flourish within a community, but they are compressed within the constraints of their singular connection.

“Love nourished itself through perpetual criticism of outsiders. The finest proof of our loyalty towards one another was our monstrous disloyalties towards everyone else. We retreated into each other’s company to laugh at the hypocrisy demanded by society.” ~ Alain de Botton, Essays on Love

Through Industrialism and the new religion of materialism, the couple has become an insular unit, bonded to build wealth, and support each other’s self-esteem. Increasingly couples are comprised of individuals who have moved away from family units to seek success. So the support once received from a caring community now needed to be found within their own four walls. A person’s inner worth is no longer determined by their role in a broader community. It is pegged to the reciprocal love of their partner. If their relationship falls apart, so does the foundation of their self-esteem and, ultimately, their sense of self-worth. Removing Maslow’s brick of Love and Belonging means that Esteem comes tumbling down as well.

“The pleasures of depending on someone pale next to the paralysing fears that such dependence involves.” ~ Alain de Botton, Essays on Love

And this, ladies and gentlemen, is at the heart of why monogamy has become so serious.

No longer is it inheritance driving the push for sexual exclusivity, but our ego. We have become dependent on our partners for all our needs — safety, love, belonging and esteem. Thanks to the romantics, we also link fidelity with love and adultery with lack of love. Therefore if our partner remains faithful, then they love us. Therefore, we are worth loving, and our self-esteem stays intact. However, suppose our partner cheats on us. In that case, we immediately believe it is because they don’t love us, which brings into question our worthiness for love. And this is why infidelity creates so much hurt and confusion. It is not necessarily about our partner’s actions; it is what these actions potentially say about us.

Materialism and individualism have created insular family units where our ‘everything’ depends on one person. When all of our eggs are in one basket, dropping the basket will create an almighty mess. Fear of this mess is ever-present, and much effort is invested in protecting the basket. In this way, I think it is not love that is the motivation to maintain monogamy, but fear — fear of losing financial support, social status and connections, self-esteem, and self-worth. Monogamy is a way we try to mitigate these risks and, once a tool for protecting assets, is now a means of protecting our self-esteem.

What is normal today?

The pattern we see today is that individuals have a series of hook-ups, short-term interludes or co-habitation trials until they find their “one true love”. For many, their relationship adventures and sexual experiments are geared towards finding the “deepest love” that will drive them to make the common commitment to sexual exclusivity.

With settling comes the cessation of promiscuity, and the individuals enter an agreement to cast away their previous libertine behaviours in favour of a dedicated sexual relationship. Maintaining monogamy is seen as a performance indicator of their love by those within and outside the couple. The strength of the monogamous relationship is also an artefact of how worthy each is of love. A successful monogamous relationship is good for the ego.

However, it is also completely normal today for this coupledom to come crashing down and for the major cause of the relationship breakdown to be infidelity [12]. Just as the expectation of monogamy is normal, so is the occurrence of infidelity. This is further evidence of the law of polarity and that the opposite notions of monogamy and infidelity, whether we like it or not, exist concurrently.

It is also normal for those in a monogamous relationship to wish that they weren’t. One study suggests that the vast majority of men (74 per cent) and women (68 per cent) would quite happily break their exclusivity pledge if they knew that they would not get caught [13]. These statistics show that it is normal for people to be engaged in sexually exclusive relationships through a sense of obligation, not through choice. As succinctly put by Adam Phillips:

“Not everyone believes in monogamy, but everyone lives as though they do.[14]

So while entering monogamous relationships is normal, so is the lack of belief in and maintenance of them. Having lovers or wanting to are also common, but what differs from our ancestors is the amount of judgement and vitriol attached to these actions. Affairs were once seen as a sign of vitality, a lust for life and an expression of love. Now a person who cheats is viewed as faulty, undisciplined, weak, flawed and exhibiting an abhorrent lack of love for their partner.

There is very little consideration given to how the structure and expectations of the relationship, and their misalignment with our humanity, could have contributed to the relationship breakdown. When infidelity does happen, it is normal for the aggrieved partner to protect themselves by deciding that this person was ‘bad’ and was not the right ‘one’ for them. We believe so much in the institution of monogamy that when things fall apart, we don’t question it but instead opt to question our choice of pledge partner. We would rather seek to dissolve the relationship and break our promises than question the suitability of the promise itself.

As outlined by Michele Scheinkman, people have a greater tolerance to engage in the destructive processes of divorce than to have constructive conversations about the reality of our human relationships.

“American culture has great tolerance for divorce — where there is total breakdown of the loyalty bond and painful effects for the whole family — but it is a culture with no tolerance for sexual infidelity.”[15]

To my idealistic and naive viewpoint, this appears like an ignorant preoccupation with one side of a coin. Although, as I have suggested, our modern egos are far too fragile to consider bringing greater comprehension and compassion to infidelity. We seem to fear loss much more than we long for love. We respect our reputations and man-made rules more than the complexity and potential of our hearts and minds. The result is that we close ourselves down and protect our vulnerabilities rather than open ourselves to understanding and allow the development of creative solutions.

So, let’s recap what about monogamy is normal today: It is normal that:

  • People will have been promiscuous (potentially non-monogamous) before pledging sexual exclusivity
  • Each individual in the couple will expect the other to be faithful to them
  • The couple equates the other’s ability to remain faithful as an indicator of love
  • While in the relationship, most people will have the desire to cheat
  • Around half of the relationships will dissolve within several years, on average eight years to separation and 12 years to divorce. [16]
  • Infidelity will be the likely cause of the relationship breakdown
  • The aggrieved partner will blame the failure of the relationship on the inability of their partner to uphold the expectation of monogamy rather than question the expectation itself
  • The ‘cheater’ will feel like a failure due to their inability to quell their natural desires and uphold the gold standard of modern morality.

What is glaringly absent in this picture of normality is the expectation of infidelity. Despite all the statistics showing the prevalence of desired or actual adultery, no one is saying they expect infidelity. They expect monogamy which has a 50 per cent success rate. And yet they don’t also expect infidelity, which is a key cause of the 50 per cent failure rate.

I’m sorry. Is it just me, or does this state of normality sound absurd? The current state of ‘normal’ monogamy is a fragile façade covering a tumultuous state of tension. Monogamy could be likened to the Titanic — the unsinkable moral standard — one that will never let us down. But the fact is, when we look at the normal state of monogamy today, it is letting us down badly. People are drowning in despair because of broken promises and doubting themselves when they fail to fit the expectation of exclusivity. As Esther Perel states:

“despite the fact that monogamy is a ship sinking faster than anyone can bail it out, we continue to cling to the wreckage with absolute faith in its structural soundness. “

It appears that what is normal is living in the delusion that monogamy is working for us in its current form.

The limits of loyalty

Adam Phillips argues that

“the most difficult people to be unfaithful to are one’s parents.”[18]

The sense of obligation we have to our parents may be preventing us from questioning the crazy nature of normality. We likely saw our parents work through the highs and lows of a monogamous marital model, and we turned out ok, didn’t we? If our parents succeeded, we would have been shown the way and have a standard by which we feel compelled to live. To go against these righteous role models would be sacrilege and risk the receipt of any worldly resources they may leave behind.

However, suppose our parents failed to maintain a monogamous relationship. In that case, we can (very arrogantly) assume that it is because they didn’t do it right. We have many more resources available to us and are sure to find fresh approaches to make our love last. For if we begin to question our own parents’ faith in monogamy, we will be insulting all they have stood for. Criticising and dismissing all their effort in coupledom may be far too much to bear. Or an even more grave outcome is that we could be called to question the eternal hope of ever finding the perfect partner and living a happy life in coupledom.

We must continue believing in the possibility of happy-ever-afters for our mental wellbeing. And yet, when we embark on monogamy, how much mental and emotional energy is spent worrying about, preventing and dealing with the fall-out from extra-marital affairs? The following alternative is suggested:

“Perhaps we should take infidelity as granted, assume it with unharassed ease. Then we would be able to think about monogamy.”[20]

While this approach sounds perfect in theory, it does not account for the embedded association between fidelity and love and the consequences of a breach of love on the individual ego. I don’t think we are mature enough as a race to separate our partner’s behaviour from our sense of self-worth, so this suggestion is well ahead of its time. Perhaps we need to progress further on Maslow’s hierarchy to the state of self-actualisation for this state of mind to be possible. We will discuss this further in the following chapters when we delve into the role of maturity in monogamy.

Our culture of isolation, fear and loyalty keeps us trapped in delusional and destructive patterns. Even when we seek counselling to repair the wounds of infidelity, the aim is to reduce conflict by restoring compliance with the cultural expectation of monogamy. Cultural norms are not questioned, but as recognised by Betty Friedan:

“For years, psychiatrists have tried to ‘cure’ their patients conflict by fitting them into the culture. But adjustments to a culture which does not permit the realisation of one’s entire being is not a cure at all”.[21]

It is this conflict between ‘civilised’ cultural norms and essential human nature that makes monogamy a moral dilemma.

[1] normal. (2023). In The Dictionary.

[2] Seneca quoted in Coontz, S. (2006). Marriage, a History: How Love Conquered Marriage. Adfo Books.

[3] Beauvoir, S. de, De Beauvoir, S., Borde, C., & Malovany-Chevallier, S. (2011). The Second Sex. Van Haren Publishing.

[4] Coontz, S. (2006). Marriage, a History: How Love Conquered Marriage. Adfo Books

[5] Hillman, J. (1997). Re-Visioning Psychology (Reissue). William Morrow Paperbacks.

[6] Note that the existence of chastity belts is now contested and viewed more as a metaphor rather than an actual genital guard

[7] Coontz, S. (2006). Marriage, a History: How Love Conquered Marriage. Adfo Books

[8] Lord Byron, Childe Harold’s Pilgrimage

[9] Could the fact that love was to be found outside the marriage be the origin of the term ‘lovers’ for extra-marital affairs?

[10] The Origin of the Family, Private Property and the State (1884) by Friedrich Engles

[11] Beauvoir, S. de, De Beauvoir, S., Borde, C., & Malovany-Chevallier, S. (2011). The Second Sex. Van Haren Publishing.

[12] Betzig 1989. Causes of conjugal dissolution. Current Anthropology 30:654–76. In a study of 160 societies, it was found that philandering is the most commonly offered rationale offered to dissolve a marriage

[13] S. (2021, March 11). Infidelity: The Cold Hard Truth About Cheating. LA Intelligence.

[14] Phillips, A. (1999). Monogamy. Van Haren Publishing.

[15] Perel, E. (2012). Mating in Captivity: How to keep desire and passion alive in long-term relationships. Hodder & Stoughton.

[16] Marriages and Divorces, Australia, 2021 | Australian Bureau of Statistics (

[17] Perel, E. (2012). Mating in Captivity: How to keep desire and passion alive in long-term relationships. Hodder & Stoughton.

[18] Phillips, A. (1999). Monogamy. Van Haren Publishing.

[19] Phillips, A. (1999). Monogamy. Van Haren Publishing

[20] Phillips, A. (1999). Monogamy. Van Haren Publishing

[21] Friedan, B., Collins, G., & Quindlen, A. (2013). The Feminine Mystique (50th Anniversary). W. W. Norton & Company.

Originally published at on January 27, 2023.



Belinda Tobin
The Moral Dilemma of Monogamy

Author. Series Executive Producer of the Future Sex Love Art Projekt. Founder of The 3rd-Edge and The Addiction Healing Pathway.