Is it time to end it?

Ok so I've been with my boyfriend for two years now. When we first met he was going through a hard time and was drinking constantly and taking drugs quite regularly. He stopped taking drugs after we got together and his drinking cut down. We went away for a few months recently and we went from getting on really really well to getting on terribly. He would get pissed (sometimes on his own) almost every second or third night and he fell asleep on the toilet in public places a few times too. Now we're home and we don't see one another during the week really because we live an hour away from one another and he works late and on the weekend if i dont want to go drinking he'll go off with his friends instead of spending time with me. He'll drink one or two nights during the week at least and on a friday and Saturday night and Sunday day. I'm 25 and he's 24. I told him that I wouldn't want him to change just for me because he'd just end up resenting me but that I didn't want a teenager's relationship. He was upset and said he's try and change things to start thinking about me more. But tonight because I said I didn't want to go out drinking tonight because i have to prepare a lecture for monday for work he stayed at home and is going out with his friends. Is it time to let him go?? I think a guy's perspective is needed here. Am i being too demanding? I don't think so - right? I've given him two years worth of chances.