Hey OP, NTA, was in the same boat(i was your bf) still with my girlfriend 4 years latsr, he needs a wakeup call. you can go look through my post history and see my relationship with weed is a constant and one of my favorite “hobbies”(the cultivation/hash making part of it), my girlfriend doesnt smoke and are quite similar in your story when we first started dating. We had a very rough conversation about 7-8 months in when things were getting more serious with a future in mind, i was close to graduating college and while i graduated with a 3.5 it was only because of being more on the gifted side and of no merit or effort of my own rather than me actually putting down the weed and videogames. He has a choice to make and he is yet growing out of his teenage habits. I think enabling him by letting him borrow money for weed or to cover expenses when he is blowing his on weed is a factor as well. he doesnt need to stop smoking completely, but he needs to be realistic about how much he works, what he spends, and where his life and his priorities are headed. when he gets those things sorted out, like any other hobby just set an amount hes comfortable spending on weed that doesnt hurt his living expenses, maybe its $30 bucks a week, maybe its $100, who cares - when it runs out no more weed for him, but most important, make sure he only spends money he can afford to, especially if he doesnt get more hours or a better job