I haven't read all posts so maybe this has been said before, but...
A vaporizer could solve the smell-hindrance and even, I believe, help your BF smoke (vape) less material, ultimately stopping if he wanted to.
I believe your BF, although definetly enjoying his weed, is addicted to tobacco. And that's the real issue. Now, smoking cigarettes I find a more unhealthy option than cannabis, but that's me.
I smoked 5gr (top quality weed) a week, when smoking joints with tobacco.
Then I switched to a vaporizer, because I wanted to be high, but I didn't like the discomfort tobacco gave me.
Anyway, without conscious effort, my usage dropped to 3gr a week. After a week I could vape when I wanted to, having realised tobacco was the really addictive substance.
Now I vape 1gr a week, and that's if I do it every day.
Meditation and yoga are wonderful for mind and body. Tell him to do the yoga asanas high, it'll teach him something while high.

Good luck !