I would love to see a situation play out like this- a mostly straight guy falls in love with his best male friend, who's also straight. They engage in a sexual relationship, but don't want to be life partners. It's more like a friendship that just happens to have a sexual dimension to it. They're both married to women, who they are legitimately attracted to and love, and the wives completely support the sexual dimension of their relationship.
I think the TV would explode though if they ever covered male bisexuality as anything but a secretly gay man who wants to be married to a woman so he can have kids.
I completely agree with your second paragraph, but as for the story idea... I fear this fits in with the misconception that if you're attracted to both sexes, you must also have at least two partners, one of each sex. Also, I've heard stories of people breaking up with their significant others upon learning they're bisexual, because it means "twice the temptation" to cheat and they couldn't handle that. Which is ridiculous to anyone who actually understands what bisexuality is, but there you go. Your idea doesn't involve infidelity, because apparently both guys have open marriages with the wives not minding their affair, but still.
But I also think a lot of bisexual people tend to think of themselves as lesbians. I know a lot of women who are probably technically bisexual (have had meaningful relationships with men in the past and are attracted to them) but only date women and will only ever date women. That is where the tricky element of choice comes in. For instance, Cynthia Nixon saying she chose to be gay. You can't really choose to be gay but you can be bisexual and choose to identify that way. It would be hard for me to imagine Willow dating a man post-Tara (unless it was Oz). I think she just has a higher comfort level in her relationships with women. Oz is a one in a million guy. Just the perfect boyfriend. So, I don't think her identifying as a lesbian is totally just society based. I think she does think of herself that way even if it isn't accurate. And I feel like that is pretty common. Especially for a girl like Willow, who is at heart a science nerd who probably likes classifying things in neat labels. So, for Willow I think identifying as gay makes sense for a million reasons even if she is attracted to men too.
I see your point, especially since it isn't a 50/50 situation for many bisexuals, who do have a preference for one gender over the other. I suppose it's possible that Willow was mostly, if not exclusively, into women, so it made more sense for her to identify as a lesbian post-Oz.
I do think you can convincingly fanwank that she was a lesbian all along. I think being young and knowing you are supposed to feel certain things about boys and then having this best friend you like more than anyone in the whole world. You can convince yourself that you love him. That what you feel is the sort of thing you are supposed to feel. And with Oz there was clearly something missing for her because I don't think Willow is the type that cheats for no reason. BUT I don't buy it. I agree that Willow was bisexual.
I'll admit to being biased here - I don't want to think of Willow as a lesbian because that would retroactively debunk Willow/Oz, my favorite couple on the show. They were just so adorable together that it would suck to think it wasn't "real", in terms of Willow's feelings. But it is
a plausible theory. (I can't explain the cheating, really, except with some generic excuse about how you're "confused" and unsure of your feelings as a teenager.)
I actually have seen a lot of gay male characters on TV who admit to having been with women, and even having loved a woman or enjoyed sex with women before (or even after, in some cases) coming out. In tonight's episode of Political Animals, for example, Sigourney Weaver's gay son says something along these lines. Something I don't think I've ever seen on American television is a character who identifies as straight, who has in the past (or even in the present) enjoyed sex with men, without that character eventually being revealed to be in the closet.
I think this is part of the double standard that still permeats American TV, sadly. Girls can make out with other girls, experiment and become "lesbians for sweeps", because TPTB count on a ratings boost from horny male viewers who get turned on by such (if I rolled my eyes any further up, they might get stuck there). Marissa from The O.C.
is a classic example, as her attraction to girls all but disappeared once the sweeps storyline was concluded.
However, there's no such thing as a "gay guy for sweeps" because a male character's sexuality has to be set in stone, one way or the other. If he ever kisses another guy, his masculinity will forever be tainted, therefore unabling him to be a straight leading man and "get the girl" (or kick ass as an action hero, or do anything manly). And judging by many comments I've seen on message boards, from straight females who don't want hot actors to be gay because it would tarnish their fantasies about them and whatnot, it's not surprising. Our society is still stuck in the dichotomy where a man can either be manly, or gay. They're mutually exclusive. As such, even a straight male character admitting having had sex with men in the past
would tarnish his masculinity and ability to have an onscreen romance with women (which is why these are eventually revealed as being in the closet).