But it'd still be brave for Trek to have same-sex couples (or triples and quadruples, for the Denubulans out there). Not female bodies with sexless slugs, not crazed bisexual control freaks, just couples who happen to be the same sex.
I'm not too pleased about the crazed bisexuals either. Not my idea of a good role model. But then again, even some open-minded people in this thread seem to think being bisexual equals not being able to being in a committed relationship.
Yes, it's a silly conflation: committing to one gender and committing to one person. Not the same thing.
Having said this - and speculating wildly - it is possible that, given the stigma associated with homosexuality, some strongly extroverted types were more willing to express their same-sex desires. And strong extroversion, from memory, often comes with an increased likelihood of straying.
This does NOT mean bisexuality equals lack of commitment. It means that in more conservative societies, only the most extroverted are willing to reveal their bisexuality. And they're also more likely to be the ones with roaming eyes.
But as I said, I'm speculating wildly...