This is an old thread Black, but I will give you my perspective. It could be the turmoil is too much for him and he just needs to create a really mellow, safe environment. I was in a very long relationship with someone and we had a lot of troubles and she drinks every night, though not excessively. I eventually had to move out before I could get sober. It was just too difficult for me. But we're still good friends. On the other hand he could want out of the relationship and is using it as an excuse because many of us have a difficult time being honest and dealing with confrontation.
You could also post a new thread over in the Friends and Family section. Best of luck with it.