Only 25 percent of women are consistently orgasmic during vaginal intercourse.

This bears repeating: Only one-quarter of women reliably experience during intercourse—no matter how long it lasts, no matter what size the man's penis, and no matter how the woman feels about the man or the relationship.

This statistic comes not from just one study but from a comprehensive analysis of 33 studies over the past 80 years by Elisabeth Lloyd in her fascinating book The Case of the Female Orgasm (Harvard University Press).

Rounding things out: About half of women sometimes have orgasms during intercourse. About 20 percent seldom or ever have orgasms during intercourse. And about 5 percent never have orgasms, period.

In other words, intercourse is not the key to most women's sexual satisfaction.

Now I'm not knocking intercourse. It's central to reproductive . If it's well lubricated and men don't plunge in before women feel ready, it can be great fun. And it makes many lovers feel deeply connected. But contrary to what many men and women believe, and see endlessly in , intercourse is not the essence of lovemaking.

This statistic has several important implications: