is common experience for men
may be the major cause
it is proven that the only effective method to overcoming Premature Ejaculation is practice and mental conditioning.
Try the "stop-start" approach. This technique involves stimulating the penis almost to the point of ejaculation, then stopping; stimulating it again, then stopping; and repeating this until you learn to control your ejaculations
perform Kegel exercises, simply contract your buttocks for one second as though you were trying to delay a bowel movement. Do this 15 times in a row, working up to 60 to 75 contractions twice a day. The purpose of Kegels is to strengthen your pelvic muscles so that you can contract or relax as you near orgasm, delaying ejaculation.
hope this helps