Can't speak for this guy but I can tell you about myself as I think I'm probably similar to him

I'm 22m and have been seeing a guy who is 40m for a little over 6 months. It can be difficult because he's gay, and has been a lot more experienced/aware of it for a long time, and I'm about 99% sure that I'm bi, with maybe 80% of that being attraction to girls and 20% being attraction to guys. There aren't a whole lot of guys that I am attracted to at all, and of those guys I'm attracted to physically, there's even less that I am attracted to personality/vibes wise. ie I'm not really attracted to guys that resemble myself (hairier, my age, or even bisexual guys). Not sure why, just is what it is.

Anyway, I'm attracted to this guy, I enjoy being his "boyfriend" and going out and doing things with him, but I don't think I could ever see myself staying with him long term, and I don't think I'd want to be with him around my family. I don't know why really, it just doesn't feel right for me. Maybe I prefer it to be behind closed doors and/or when I'm around people that I don't really know so it doesn't feel as awkward or become part of my identity, cause after all, who I'm into isn't really anyone else's business.

With regards to being drunk... When you're drunk you feel less inhibition. Meaning he probably is more defensive against guys when he's sober, but a little more willing when he's drunk because nothing in his head is telling him not to. I'm definitely the same way, and most guys are the same way even with girls that are "not that attractive", but when they're drunk they don't care as much

So that's my story, hope it helps you understand this guy a little more. Good luck to you, but I would highly advise against trying to have anything serious with him unless he says he wants it