You probably have the so-called honeymoon cystitis, a condition not confined only to the honeymooners. It is usually associated with frequent and prolonged intercourse. The exact cause is damage of the urethra and bacterial infection by Escherchia coli, which normally lives in the intestinal tract. Once it occurs, antibiotics are required for treatment. It can be prevented by (1) drinking plenty of fluids orally, (2) washing and urinating before and after intercourse, (3) avoiding vaginal intercourse after anal intercourse, (4) cleaning/washing from forward to backward direction after defecation.