This ring true for me, too. I'm going to be moving out in the next week. I've let him believe that I may change my mind, but I'm not.
He's doing all of the things described above....not drinking, doing what he needs to be doing, and being nice and supportive. BUT, we've been through this before and I know that he'll be drinking again in the next few weeks. I know it!
I'm going forward with leaving. It's up to him to do what's right for him or not. Nothing I can do or say will change him. Only he can.