I don’t pretend this is new and original, but I’ve found it helpful to be as precise and definite as possible in terms of thinking about how people interact (guy-guy and guy-girl). (Occupational hazard.)
There’s three ways to relate to another human being. (Ok, at least three, but three for now.)
There’s the social level. This is friendship – who do we like to spend time with? If it’s mostly/exclusively other guys, then we might consider that we prefer to socialize with the same sex. That is, homosociality. Preferring to socialize with women might be described as heterosocial. “Socialize” here I think is a little more than just “who do you like to hang out with”, but it’d include that too. I’d argue that most guys are homosocial by nature; it’s easier for us to understand each other than it is to understand women. Not a big deal either way.
(The stereotypical “feminine” gay man is the exception to this. Socializing is based partly on shared interests and mindset/attitude. Friends don’t all have to like exactly the same list of “approved manly” things, but when there’s nothing in common to talk about… it’s a little awkward. Possibly this explains what has been described as “Gay Fatigue”? Tomboys or (I guess) “butch” lesbians would also be exceptions.)
There’s the romantic level. Again, one can have romantic feelings mostly for people of the opposite sex, mostly for people of the same sex, or some of both.
There’s the sexual level. No big surprise that there’s that same spectrum here – sexual desire exclusively for the opposite sex, mostly for the opposite sex, half-and-half, mostly for the same sex, exclusively for the same sex.
So, three dimensions. They’re not automatically related – being strongly homosocial is perfectly compatible with being strongly heteroromantic and heterosexual, or also with being homoromantic and homosexual. “Romance” and “sex” aren’t always linked (“correlated”) either. “Homosexual but heteroromantic” (or hetero for sex but homo for romance) would be awkward, though!
I think the tension about being bi comes, in part, from combining “homosocial” and (partly) homo-sexual with hetero-romantic. I’ve slowly realized that I’m not entirely hetero-romantic, either, or at least there’s one shining exception. Although it really doesn’t feel like the same kind of “romance”, either. Or maybe it’s just that I know that he’s not ever going to want flowers and sparkly shiny jewelry?