I understand completely. I lived with 2 SOs who smoked. If I ever wanted to quit myself, it was impossible, because both of you have to make the effort - one side cant just sit around smoking still while the other quits, it's like living on two different planes of existence, which is no good for the relationship, and one of you eventually gives in. And if you both accept that it's just fine and you sit around blazing, you fall into the trap of doing nothing together and, regardless of how stoned you get and how often you both tell each other and yourselves that it is okay, it's not. It's not fun, it's boring, and it stagnates the relationship.

If you both become active and motivated people who make the effort to do things together and live life fully while still smoking (and no, eating and watching movies doesn't count), it could work, it could work finely - but from what you've said, he has no interest in doing that.

So my only advice is... leave the relationship. Unless he decides he wants more in his life than just smoking and doing nothing (and this is something he cannot be forced or persuaded or scared into doing, he has to genuinely want this for himself) then you and him will forever be on separate planes. Unless, of course, you decide to give up and join him, but I dont advise that, and youre realizing you dont want that.

It sounds like harsh advice, but I've been here, twice. I'm not saying to give him an ultimatum, or make him choose between smoke and your relationship... that would only frustrate and confuse him. What I'm saying is think hard and evaluate your relationship and it's future. The relationship might have reached a point where you both desire different things, so it may have to end. Yes, "its just weed", but it would be the same decision to make if it was over a career, or religious beliefs, or wanting children, or a specific place to live etc. Either you both walk together on the same page, or you have to call it quits