I've seen several threads like these on other forums, and they always end up becoming a heated battleground of debate.
My two cents, FWIW: One of the problems is that men, far more so than women, tend to label themselves as they want others to see them as opposed to what their activities or feelings genuinely reflect. For example, several years back there was a guy on another forum who constantly talked about women. Loved tits, pussy, and so forth, regularly hooked up with women for sex, and even said the true love of his life was a woman. Well, guess how he self-identified? Gay. And he would argue you to the ground if you dared to challenge this. Yes, he was attracted to guys, and yes, he had sex with guys, so he wasn't straight. But he flat refused the bi label, even though friends in his personal life considered him more bi than gay.
My husband and I have a close friend who came out as gay a few years ago after being married to a woman for over a decade. Yet even now he notices women he finds attractive and says, "I would have sex with her if I were still straight" or "I'd have sex with her in a pinch." Granted, he is still dealing with some major personal baggage in his life. Is he actually gay? Possibly. Is he more bi than gay? Likely. Regardless, he's our friend and we support him.
Another issue is that some men create their own definition of what terms mean to suit their own perspectives. For example, bisexuality
must mean an
equal attraction to both sexes. (This is false, of course.) Bisexuality
must mean that you're open to a
romantic relationship with either gender. (This is also false.) To be genuinely gay, you must
never have had any kind of sexual experience with a woman. (This, too, is false.)
Just throwing this into to the mix.

Sexuality is not always complicated, but it is complex.