Hi there. Delayed ejaculation has many medical causes like hypogonadism , thyroid disorders, Cushings disease, due to pelvic surgery , drug and alcohol use. It's even caused due to stress and fear of inability to achieve proper erection, insufficient sleep, distraction because of some worry, distraction from the environment, anxiety about pleasing their partner, relationship problems,certain medications.another major cause is adaptation to masturbation. People who mastrubate a lot often have difficulty in vaginal intercourse as body and mind is acclimatized to certain masturbation techniques, postures and visual pleasure. Treatment includes sex therapy for both partners, relaxation exercises, be confident and less worried, increase foreplay by which you may get more aroused, avoid masturbation, get treated if you have any medical disease. Even weakness and feeling tired could lead to no ejaculation. Eat more nutritious foods and have sound sleep.consult psychiatrist once..