I have trouble cumming.

Hello. So (M18) I've had a couple of casual hookups in the past months, but the problem is always the same, I get hard, have sex and can go for hours without cumming. I just won't cum. I manage to get her off, I enjoy the sex, but I simply won't cum, not even if I masturbate.

I don't like this because I feel like it's unattractive from my side, and I don't want women to think that they're not hot or that they're the reason why I wont finish. Any other men had this issue? What have you done to fix it?