As you've seen, weed addiction can be nastier than most people would think. I don't have a lot of advice to give since I was the pothead and not in a relationship with one. All I can say to you is that he won't quit for anything/anyone but himself. Even if he does, he won't stay quit. That I can guarantee just about 100%. The thought of going through the hell I've gone through for someone else is almost laughable, as sad as that may sound. I guess you have a choice to make. Do you want to stay with him and hope he comes around one day (nothing you can say or do will make that come quicker as you've seen), or do you want to go through your life without your ankle shackled to a cinderblock? The first sentence in your post says it all.