I need help!

Ok, I've been with the same guy for 4 years. He is I guess what you'd call my "first love." 
Anyways, about 2 years ago he started becoming obsessed with playing Xbox, smoking, and doing nothing but staying in his room all day. See, we live together. But he has kinda like a "gaming room."
All he ever wants to do is stay back there. When we talk all he wants to talk about is that. 
I have gotten dressed up for him and him ignore me. I have straight up told him if thing didn't change I didn't know if I could take it. But I dealt with it for 2 years. But now I think im getting to the point where I don't think I can stand  it. But now it's worse! He sleep all day and then stays up all night playing Xbox. And he doesn't want to look for a job. (He's also 21) I'm not a pushy girl friend, I never forced him to do anything to make him unhappy. I'm actually pretty supportive of any of his decisions. But he ignores me. And he doesn't understand how it makes me feel. I've explained, I've threatened to leave him! And he continues to do it. I think I know what I have to do.. but there is still a peace of me that has hope he'll change. But maybe he just doesn't care.. I don't know I need help. 😢