I agree, try to spend more time with him (not that you're not doing so, I don't mean to imply that), but just so that he won't feel like he has the opportunity to drink as much? For me personally, I think drinking became a habit as much as an addiction. Even if I didn't /want/ a drink, I would have one just because, 'Well might as well, I've got nothing else going on'. Maybe he has days like that too, and if you're around it might help to deter him. That being said, if he's been drinking and you don't want to be there for that, I completely understand! Good luck, I hope things improve for you both.