Hi,
Welcome to ehealthforum,
Having adequate foreplay before indulging in active vaginal intercourse or practicing the 'start and stop' technique to prolong the male erection (and avoid early ejaculation) would help in your situation. Discuss your problems/feelings with your partner and go about with having intercourse with mutual understanding and communication. If the problem persists, visit your gynecologist/sex therapist for counseling and couple therapy to get the problems identified and resolved. All the best.
Take care.