I’ve always found this fascinating because watching people who’ve experienced persecution for their sexuality, then persecute others for their sexuality, is astonishing.
I think a few factors are at work: for many, bisexuality breaks up a simple dynamic of gay or straight. By introducing the concept of a sexual spectrum, it complicates the narrative.
I also find a lot of mainstream society’s attitude to male sexuality is still male-dominant, when you break it down: at the core is the idea sex with a man is the best.
For example, a man who slept with another man but identifies as bisexual, is not bisexual, but in denial of his homosexuality. Even if he has a relationship with a woman, he will still be percieved as gay by many.
A woman who sleeps with another woman but identifies as bisexual, is not in denial of her homosexuality, but merely adventurous. When she again has a relationsip with a man, she will be percieved as straight, or bi in the sense of straight but prone to sexual exploraition.
The odd double standard at work here definitely exhibits a gender bias.
Sort of similar to the way a straight man watching two women kiss and being turned on, is considered the mainstream norm. Yet a woman watching two men kiss and being turned on is not: the woman should be, what, outraged? Threatened? Sexually dissasociated from the scenario?
Underlying this reaction is the “threat” of male homosexuality: reminding the straight woman that sex, with a man, is always best, and once a man “crosses over”, he cannot be “reclaimed” by a heterosexual relationship.
The man’s gaze doesn’t experience this “threat” when watching two women interact.
Note: By mainstream culture, I mean these are opinions/perspectives on sexuality I’ve heard in more traditional parts of Western society repeatedly, as if it goes without saying that these perspectives are “obvious”, or “true”.