Masturbation
This mostly affects men. When a man becomes addicted to masturbation it is harder for him to reach orgasm because his body is used to one thing. “He becomes conditioned to a certain sort of manipulation that allows him to ejaculate and that sensation is lost when he’s with a partner,” says Dr Harry Fisch, a sex therapist. When man responds better to making himself ejaculate, making him orgasm while having sex can be really hard.