If a man has no medical problems what else could be the cause for lasting only about a minute in bed if he is 25 and you're 24 and he's the only guy you've slept with so could it just be you?

nothing is wrong with you, but he suffers from premature ejaculation. He should get it checked out as that sexual disfunction sometimes can be corrected. Or, simply dump him and search for another guy to sleep with...