Did you just celebrate Valentine's Day with your man? Well, keep him out of Tinseltown!

From Scarlett Johansson to Angelina Jolie to Paris Hilton, some stars should never be let loose around your guy.

Sultry sex goddess Johansson is rumored to be the cause of Justin Timberlake's recent split from Cameron Diaz. Jolie has been blamed for destroying one engagement and one marriage. And it seems like there's no guy Hilton fancies more than the one who is dating her friend.

But what is about these girls that gets the guy?

“It an ego thing,” said L.A.-based actor Ross Matthews. “These girls are like ethereal species. If they show an interest in you, suddenly there's no way you can use the brain that’s in your head. All you can focus on is living out that fantasy.”

Take Johansson, for example. Timberlake and Diaz reportedly broke up because Justin went behind Cameron’s back to cast Scarlett in his music video, even though she had a crush on him, US Weekly reported.

Lo and behold, over Super Bowl weekend, Timberlake and Johansson got hot and heavy at a Miami after-party, the New York Post and In Touch Weekly reported.

"As they left through the back, Justin was leaning against the wall and Scarlett came up, leaned into him and did a sexy little dance, grinding into his body," said Post stargazers.

But who’s the crème of the crop when it comes to femme fatale behavior?

“Angelina Jolie for sure,” said Taylor Evans, an actress and nightclub promoter for a number of L.A hotspots. “She would have to be a woman’s worst nightmare if she was around your man.”

The gorgeous screen siren certainly has a rep for raiding more than just tombs.

Fresh from her divorce from actor Jonny Lee Miller, Jolie married Billy Bob Thornton in 2000. But shortly before their wedding bells, Thornton broke off his engagement with his long-time fiancee, actress Laura Dern.

Jolie, of course, has also been accused of being the "other woman" in the divorce of Brad Pitt and Jennifer Aniston, though they say they were just friends while he was married.

One would think in a city filled with models, actors, singers and surfers that there would be plenty of men to go around, but it seems Hollywood’s leading ladies would all rather dip and drown in the same gene pool.

“Hollywood has a very elite ‘it’ group,” said Evans. “Once one guy breaks into the niche, all of sudden the other girls want what they can’t have.”

Or shouldn’t have, more like it.

Not even a week after Paris Hilton publicized her break-up with fiancé Paris Latsis, she was spotted with Mary-Kate Olsen’s boyfriend, Greek shipping heir Stavros Niarchos, the New York Post's Page Six gossip column reported in 2005.

Olsen said she always considered the Hilton socialite a friend, and was shocked by her actions.

"Paris and I always only had nice things to say about each other. Now I guess you can tell we're not talking,” she told W magazine.

And if you thought that cat-fighting over boys was a phase that dwindles with age, think again.

Heather Locklear is allegedly still trying to get back at fellow actress Denise Richards for dating her ex-husband, Bon Jovi star Richie Sambora.

But Richards is quick to defend herself against accusations that she caused their marriage collapse shortly after leaving her own hubby, Charlie Sheen.

“I wish Heather well and she knows that there was nothing that happened during either marriage,” Richards told TMZ.com. “But unfortunately our friendship had to dissolve.”'

So why do these starlets supposedly steal what isn’t theirs?

“It almost seems like a game they play in Hollywood,” suggested Evans. “It becomes a challenge to steal the partner of your so-called friend. Once you’ve succeeded, you move on.”

“It’s a talent a lot of women in general have,” added Matthews. “Celeb status or not, ladies who know how to use their sex appeal can usually manage to swindle even the most devoted man from his gal pal.”

But is it really possible to steal a guy? Or is he usually waiting on the shelf for purchase?

“Often the guy is afraid of commitment, bored or unhappy; therefore cheating is a way out,” admitted Australian relationship counselor Anita Smith. ”The initial excitement of a new partner is always a novelty, and many guys and girls have a desire to feel loved by more than one person.

"There is usually some sort of problem going on behind the scenes before he leaves, but having a temptress hanging around certainly stirs unnecessary trouble,” she added.

So ladies, be safe and keep your man well away from the 90210 zip code. While there is no denying it takes two to tango, plenty of ladies in Hollywood have no trouble taking the lead — and taking your guy.