I would also suggest that it could even be completely unrelated to alcohol -- a very small percentage of men end up with erectile dysfunction at a young age, and if he refuses to go to the doctor about it then there's just no way to know.
Don't worry, I'm certain it's not you -- we're always much more hung up on our own bodies' faults than our significant others are
. When my AH is drunk he'll say some very mean things about my physical appearance, but then there are times that he'll wake up in the middle of the night to tell me he had a dream that paparazzi were chasing me because they were completely fascinated at the shape of my butt. I try to keep in mind that a few pounds, a few stretch marks, etc. would not turn off my desire for him, so the chances are it also won't turn off his desire for me. Never had an issue with him demanding sex while drunk -- nothing works then -- but thankfully it all still works when he's sober (he's 51...A for 30 years).