Gosh, here's a shock:
A woman's sex drive begins to plummet once she is in a secure relationship, according to research.
Researchers from Germany found that four years into a relationship, less than half of 30-year-old women wanted regular sex.
Conversely, the team found a man's libido remained the same regardless of how long he had been in a relationship.
Of course, the man man may want sex as much, just not necessarily with the same woman he's married to. Another shock, I know.
(Woody Allen in "Sleeper," on awakening and answering the question of how long since he had last had sex: "200 years -- well, 204, if you count my marriage.")