Nope. You can never quit. Marijuana is more addictive than cocaine and heroin put together, or as I like to call it, coceroin.

Of course he can quit. Cannabis doesn't build a physical dependence, so he's not going to get sick from quitting. He may be a little irritable and have some sleepless nights, but he should be fine. In other words, he will quit on his own if he feels it is worth it.

Personally, I don't think it's the weed that's ruining your relationship, it's your boyfriend's attitude toward life that's being projected through his smoking habit. Cannabis only changes people into lazy, worthless slobs if they were already that way to begin with. Keep in mind, when a relationship starts to go bad, the couple usually blames anything they can before it all comes crumbling down.