That, my little semen-less friend, is probably delayed ejaculation, a penis problem that roughly 8% of man have. Symptoms of delayed ejaculation are..inability to achieve orgasm despite sexual stimulation and normal arousal, or not being able to orgasm in under 45 minutes. Most men with delayed ejaculation can only climax from masturbation. It's the least common sexual dysfunction men have, according to the almighty internet. And it probably makes you feel pretty shitty, since men are perceived as chronic premature ejaculators, or sex-hungry sex-fiends who can come from sex. SEX. Anyway, don't take it personally. Unless you are smelly and horrible, it's probably either an endocrine problem, the result of drug and alcohol use, or a result of trauma to that area. A lot of prescription drugs, particularly SSRIs and antipsychotics can mess shit up for him, too. But, barring any of that, the most common cause of delayed ejaculation is that men get used to how masturbation feels before they become sexually active. They lose their virginity to their hand, and that immensely enjoyable sensation is what gets imprinted in their brains as "pleasure." So, when you're having vaginal, anal, or oral sex, it doesn't mimic the tightness, particular friction, and roughness they get from hands. On the same note, what a man sees, hears, tastes, or smells when he learns to masturbate can get encoded as "pleasure," making anything different than that seem somehow less arousing. Which again, is more of a problem with him than with you. But whether he has some kind of brain-eating amoeba that destroys his endocrine system, or you're just not that "busty brunette" he saw in that 1983 issue of Hustler, or your vagina doesn't feel like the hand of a man who's been working in the fields the majority of his adult life, the treatment is pretty much the same. So if you like this dude enough to go through with it, here's how you can fix it. Have him masturbate in front of you, until he's comfortable ejaculating in your presence. Then, gradually replace his hand with your hand. Then, replace hands with the desired orifice. The whole point is to get him to slowly accustomed to ejaculating with another person, and to be aroused by different things. If none of that shit works, hypnosis and meditation apparently work too. So either it's delayed ejaculation, or you're the worst at sex. Have a nice life!