Not to say that men wouldn’t ever need a FoF (I think it’s a good idea for everyone to have) but: if you’re in a relationship that includes some degree of financial mingling with a woman with less earning power than you, you should *encourage and help her* build up a FoF. Why? Because it is poison to a relationship when you realize that someone might only be staying with and putting up with you because they’re financially dependent on you, whether true or not. You *want* your partner to be financially independent of you, if only so you can assure yourself that your relative earning power is not inherently coercive.
That doesn’t mean you have to earn the same amount to be equals, relationships can thrive from asymmetrical contributions in different categories as long as it roughly evens out in the end. But each party having enough set aside to survive for a couple of months if need be is emotionally liberating and good for every non-abusive member of the relationship.
(It should go without saying but if you proactively assist with building an FoF for your partner, you don’t have the right to oversight into it. “How’s your FoF right now, if you need more let me know and I’ll spare what I can this month” is enough, you don’t get to know numbers and specifics. If that makes you suspicious and you worry you’re being taken advantage of, you already have relationship problems to address.)