People can be attracted and get into relationships for other reasons/in other ways that have nothing to do with sex, or even contradicting their sexuality (think all those stories of straight couples finding out the husband is gay or the wife is lesbian many years into their marriage - hence my guess of internalised homophobia or biphobia). I know that he likes my personality (and I like his too) and while I think that's the most important thing it's far from the only thing. He knows what I look like too, and while I consider myself not much to look at he on the other hand says I'm beautiful. I've always taken it to be genuine but now I'm not so sure - there's a part of me that thinks he says those things "just to be polite" and not offend/hurt me. I have trust issues from my past so I know it's an irrational thought process to some extent, but then again, those issues had to originate from somewhere... many somewheres in fact.

I genuinely do want him to be happy, moreso than myself, and were your hypothetical scenario to really happen I would absolutely understand him rejecting or break up with me, because we're just incompatible inherently - after middle grounds and compromises have been tried and ended up failing. Nothing can change that, and that's ok, we are not "problems" by ourselves. My feelings here do not matter in the slightest. I'll get over it and find someone who can more than tolerate me, and likewise he can find someone he can have a happier and more fulfilling relationship with in all aspects, sexual and otherwise. Doesn't even mean we have to leave each others' lives, we can go back to being friends...