sex is very complicated activity. A child recognizes sex at the age of three once it finds difference in urinating behavior and becomes curious. This curiosity remains for rest of the life. At the age of 15 the urge begins and occupies utmost activity in ay to day issues. A partner with similar urge joins. First experience(s) is marvelous and enduring, long standing. Gradually it reduces first in a female partner then in male. some men have sexual urge even after 80 plus, though not getting goo erection. sex is not merely intercourse. couple should feel, understand good companionship of sharing and caring is also part of sex.