When he's not that into sex: some guys' sex drives are stuck in low gear. So what's a red-blooded chick to do? Cosmo steps in.(LOVE AND LUST)

* It's a widely held belief that all men are total horn dogs turned on by damn near anything. That's why when your guy rebuffs a roll in the hay with you it's hard (make that impossible) not to take it personally But here's a dirty little secret few people talk about: It's alarmingly common. According to a Cosmo Web poll, 39 percent of readers have, at one time or another, had boyfriends who wanted sex less often than they did.

One of the reasons for such a surprisingly high number may be that as completely liberated chicks, women today think nothing of vocalizing their sexual needs. That alone has made any desire disparities more conspicuous than they've been in generations past. But that's not the whole picture.

The truth is, some men as young as in their 20s and 30s just don't want sex that frequently. And we're not talking about a temporary dip in his sex drive--that happens a lot, for all kinds of reasons [see sidebar]. Many of these guys never had much desire to begin with.

"The obvious assumption would be that he's gay, cheating, or not attracted to you, but he just may have a lower sexual set point," says Stanley E. Althof, PhD, professor of psychology in the department of urology at Case Western Reserve University. There's nothing wrong with you; it's just in his makeup.

Although there's no way really to measure a normal sex drive, most experts agree that if a guy feels the urge to get it on with a partner or masturbate at least once a week, his erotic appetite falls within the healthy range. Still, that's no consolation if you want sex more often than that. Here, we dissect his passion problems and deliver some helpful advice.

It's Physical

Before resigning yourself to a sex life in which your vibrator figures more prominently than you'd probably like, you should first try to pinpoint what's causing your man's erotic apathy. If he only wants to knock boots once every two weeks or less, he's most likely suffering from a low libido, stemming from a physiological or psychological issue.