My boyfriend has two girlfriends, Me and Mary Jane

So I've been with my boyfriend for going on 10 months, but we've been talking to each other for over two years. For the past few months I honestly think I have fallen gead over heels for him. Hes all I think about and I've never felt this way before. I'm not bored of him, he doesn't irritate me easily, we don't argue very often and everything is pretty perfect. But he has one other love... He's a huge weed smoker. Dont get me wrong, I haven't got a problem with it, and i enjoy smoking too, but he has a big problem with it, hes getting himself into debt with it. Can someone just give me some advice and help me out?