Boyfriend Problem?

So my boyfriend and I have amazing sex but he can never cum?

He talks to me about almost finishing and our condoms always break.

What the hell are we doing wrong? 😂

We are both stoners and he has done other drugs before but I’m not sure how that would effect him being able to finish? We can go for 2 hours plus and multiple times in a day so I don’t even know how he can’t finish?