You are very possessive of sexual labels overall, regardless of which one you're specifically referencing. Are you the type that dislikes having your peas and carrots mix on your dinner plate?? You need very clear & distinct boundaries??
Then chew on this (haha, pun). You shouldn't confuse different parts of a person's sexuality with each other. There's the record books (the actual sex you have), the sociological portion (i.e., the label you express to people, the conversations you have, the communities you loiter), and the psychological portion (the labels you most closely identify with, the sexual fantasies you have, you inner most thoughts and feelings about sexuality and sex).
So let's do a case analysis. There's this guy, let's call him John Smith. His record books; he's happily married to a woman he loves...let's say 15 years now, so he's 40 years old. And they have regular sex. But his wife is not as attractive as she once was, and he had a few GAY bj's (UH-OH) in college. So he figures, why not?? It'd be easier than girls. So John Smith goes on the DL every couple of months. Sometimes he has a friends with benefits...they'll fuck in the woods against a tree, a fucking tree hugger, gee wiz! But it never really lasts as he's just horny and doesn't want the strings. So maybe his record books would be labelled bisexual & heteroromantic.
Sociological portion. John Smith works in an office setting where his hetero-normative co-workers just assume he's straight--big shocker there. And the few times it comes up, he joins "the straight team"...a gay guy might reference the group he's in when making a straight person joke let's say. But the subject doesn't really come up that much because most of the guys and gals he knows are also married. But if it doesn't, he just says he's straight without really thinking about it much, just like most of the others. So the guys talk about hot girls sometimes, and he enjoys it and joins in. But he never talks about hot guys, or hot gay sex, and whenever it comes up, he gets antsy and nervous cause HE DOESN'T WANT TO TALK ABOUT IT!!! None of "the guys" do, it's just too weird for them. So let's say this section would be labelled cautiously straight.
Now the psychological portion. He does hook up with guys, so John Smith probably thinks about it from time to time. But who knows how far he actually goes...he does love his wife after all, but that relationship doesn't "excite him" anymore, and he doesn't want to admit to himself that he's not a young buck anymore. So he wants to break the rules and feel like he's a big shit again. So sometimes he only wants a blow job, but other times he wants to fuck a tight hole. BECAUSE THAT'S SO WRONG. I imagine he likes to think about it before he wants it, when he's searching for a guy on the DL. But not the rest of the time, he would hate to be thinking about it on shift in front of the guys, THAT'D BE SO AWKWARD. And definitely not in front of the wife, it might give him away. He likes fucking her in pussy anyway, and he really loves her so that's not really a problem. Plus, he doesn't like to think about it cause it makes him nervous, obviously. He doesn't want a divorce, he's built a life with this woman. It really only comes up when he's horny and the wife isn't available...she's too tired tonight or she's on a business trip. Her libido is on the way out now too, while his is still strong. Maybe, in those times, he'll flip a guy on his back and pretend the anus he's fucking is actually a young pussy. So let's say this section would be, like the first one, bisexual and heteroromantic.
So, wise guy, is he straight, bisexual, or gay?? But what's more is, WHO GIVES A SHIT?!?! What any business is it of yours to know what John Smith's "true" sexual orientation is?? I suppose it might also completely shock you that maybe, JUST maybe, a person's sense of self might be a LITTLE more complicated than a simple one-word answer could effectively communicate. And that maybe expecting a person to be able to happily summarize their sense of self into one word just because that's what you want from them (the ONLY thing you want from them) might be a tad arrogant and pretentious of you. Nobody owes you ANYTHING bub, and that includes a sexual label (which doesn't even belong to you) that you can be happy living with.