Hello,
Welcome to the ehealthforum and I am really glad to help you out. What you are having is premature ejaculation.
Depending on when premature ejaculation has started, it can be primary or secondary. The treatment of premature ejaculation is having a psychological session with the couple, stop-start or squeeze-pause techniques, desensitizing creams and SRRI (selective serotonin reuptake inhibitors) in severe cases.
I would suggest you to consult a venereal and sexual health expert and discuss this with him. It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.