When having sex, I come much sooner than i would like. I used to not be able to come at all when I had sex, or it would take a long time. But now since I met my girlfriend and we've had more sex than I ever did before, I come much sooner. I've even noticed that when I masturbate now, I come quicker than i used to also. Any advice? I want to have sex for a lot longer with my girlfriend.