Cannabis smoker

I've been with him before and I knew back then that he sometimes smoked weed, but we're back together after a year of separation, and now he's pretty much taking it whenever he can. He also smokes regular cigarettes; last time we were together he said he was trying to give up, but now I don't have a clue if he is. I just feel like this time he's more concerned about his next joint rather than me, but I just can't express how much I love him, he's such a nice guy and a really good boyfriend, but his drug habits do concern me. I don't know whether he's doing it under peer pressure but I think that might have something to do with his drug habits.

I want to say something to him, 'cause I think I know him well enough to assume that if I say it's a problem for me then he'll see its a problem for him too and hopefully he'll want to stop or at least cut down. But how easy is it to ween someone off cannabis? I also don't really want him stopping just for my sake, I want him to do it for himself too but I know that would never happen. But also there IS this small part of me that thinks that he might just break up with me if I'm getting in the way of his cannabis; it's something that I think has changed him a little and although I know I still love him, he's more likely to be the exact person I loved a year ago, rather than the drug-addicted one now.