He has to not only want to quit but have to be sufficiently motivated to quit and stay away from it.
I was in a 8 yr relationship with someone that was 5 yrs clean when I met him. After being together 5 yrs he started using again. Some of the things that he told me were that he truely wanted to quit. When he did not have money he did not smoke crack and was sickened that he actually did it, felt horrible about it, wanted to turn over a new leaf. I believe that he was entirely sincere in his feeling that way and that most crack users do feel that way. Then the minute that he got money in his hands his reasoning would just go and all he could think about was crack.
While he is wonderful when he is not using (when he has no money) and I am sure he is a wonderful person he still will have that compulsion to smoke it and there is nothing that you can do about that... As the other posters stated , if you stay with him long enough he may get violent and threaten you for your money. My ex broke my arm one nite and the following day threw a chair at me and broke my ribs. He did 6 months for it and I have had to get several restraining orders on him and have sent him to jail several times.
There are too may people out there that you can have a relationship with that you do not need to worry about your stuff being stolen, your money being stolen, being threatened
the only way that they can get off of it is to hit rock bottom... Bottom is different for each person. It is just a matter of how bad things get before they decide to make the changes. And even at that there is no guarantee that once he hits that bottom and you are there to pick up the pieces for him that he will stay clean.
If you want someone to talk to for support and to learn how to not enable him check for a nar anon chapter in your area.
It is like alanon but for narcotics. If you can't find anything try calling alanon or narcotics anonymous.
I wish you the best of luck with the situation