Definition of Sexual intercourse - painful:

For both men and women, pain can occur in the pelvic area during or soon after sexual intercourse. It can happen at any time during sex -- for example, at the time of penetration, erection, or ejaculation. Eventually, if pain from intercourse is ongoing, you could lose interest in any sexual activity.

The medical term for this is dyspareunia.

Common Causes:

• Intercourse too soon after surgery or child birth
• Vaginal dryness or inadequate lubrication (for example, from insufficient foreplay)
• Menopause (vaginal lining loses its normal moisture and becomes dry)
• Vaginal infection
• Reaction to the latex of a diaphragm or condom 
• Prostatitis -- inflammation of the prostate
• Genital irritation from soaps, detergents, douches, or feminine hygiene products
• Herpes sores, genital warts, or other sexually transmitted diseases
• Urinary tract infections
• Endometriosis
• Vaginismus -- involuntary contraction of the vaginal muscles; this may be a result of ongoing painful intercourse as well as a cause
• Ill fitting diaphragm
• Sexual abuse or rape
• Hemorrhoids
• Certain medications