Sometimes an addict real has good intentions to want to quit and stay sober, but often times this is very short lived. Usually these bouts of wanting to change their lives comes from a really bad hangover (and I think most can relate even if we aren't alcoholics the times we got too drunk with a massive hangover and stating we are never going to drink again!), problems in relationship of one spouse about to leave, DUI etc. but their addiction takes over and they are powerless to stay sober. To fancy the idea of wanting to change because your in a sh*tty situation at the moment and really changing your whole lifestyle are two different things.
Think of it this way... What your Abf is going through with alcohol is the same thing you are going through with him. He wants to leave drinking. You want to leave him. Both of you are really struggling with how the hell you are going to do this. The both of you just have different addictions, but the struggle is the same.