Richards and Sambora apparently began dating mid-March. Locklear filed for divorce from Sambora in January. That leaves six whole weeks of healing before Denise and Richie discovered their previously purely platonic feelings had developed into something, well, less pure.

Richards and Sambora seem to be under the impression that the big issue is whether or not they physically fooled around for the first time before or after the day that Locklear filed for divorce. If only they could convince the media and the public that there was actually a chaste cushion of a few weeks, all would be forgotten. That scheduling clarity could expose the cloud over this new relationship issue as the big misunderstanding it really is.

But they're wrong. Why? Because to Heather Locklear, and a lot of other people who have suffered the same fate, this feels like a betrayal. Denise was at one time Heather's best friend. Our friends are our friends because we place trust in them:  to keep our secrets, to tell us when we have broccoli in our teeth, and not to make the moves on our husbands or wives when we're not looking.

Whether it's been six hours, six weeks or six years, dating a friend's ex is almost always seen as betrayal of the friendship. Why? Because you're willing to trade everything you've shared with your friend for whatever is behind door number three.

Susan Shapiro Barash, teaches gender studies at Marymount Manhattan College, and is the author of Tripping the Prom Queen: The Truth About Women and Rivalry.  She says, "Dating a friend's ex devalues the female friendship because the message is: he's worth pursuing even if it means losing our friendship. I'll take this guy, if I can get him, over the friendship we've shared. There's no trust anymore between the women."

Barash adds, "Women date other women's ex-husbands or ex-boyfriends because there is the sense for women that there isn't 'enough pie.'  Since it's all about limited goods, why not go after your friend's ex?  He's a good catch and there doesn't seem to be enough good catches. Women do this and justify it with this way of thinking she didn't want him anymore and he's worth having. It just isn't that simple -- it's too territorial and too sensitive an issue to be easy on the friendship. It is all about competition and envying -- thus wanting what your friend has or has had." 
 

The fact is most friendships will not survive a betrayal of this kind. In Locklear's case, it doesn't really matter whether her friend and her husband started messing around the day before or the day after the divorce was filed.

She'll probably always wonder whether her friend was listening to her pour her heart out and then using the information to her advantage. She'll wonder if her friend's "You deserve better than him" pep talk was genuine, or merely an effort to get her out of the picture. And worst of all, she'll always wonder if two people she trusted were betraying her right under her nose.

Dating a friend's ex isn't just a bad idea when marriage is involved. It's a bad idea altogether.

You're Going To Do It Anyway?  Here's How to Soften the Blow...

Reconsider and just say no.

Talk to your friend about your feelings before you ever act on them. Tell your friend that you value him/her as a friend and that the friendship is more important to you than dating his/her ex.  If your friend asks you not to date his/her ex, respect their wishes. Wait at least a year after a breakup, two years after a divorce is final. 

Lissa Coffey, author of What's Your Dosha, Baby says, "If you want to date a friend's ex, you go to the friend and ask how she would feel about it.  If the friend gives you the green light -- then the ex is fair game. Many times the friend has moved on with someone else, or has just totally let go of the ex and doesn't care if you date him.   

"However, if the friend says that she is uncomfortable with it, or you're crazy after all the bad stuff she's told you about him, or that she feels that would be disloyal to her, then you should back off! Obviously there are some emotions there that need to be worked out. Men come and go but girlfriends can be there for each other through all the drama.  It is important to nurture these friendships and respect your friend's feelings."

Reports have begun to surface that the tryst between Richie Sambora and Denise Richards is over. This means she traded her closest friend on the planet for a couple weeks of fabulous sex and a newsstand's worth of bad PR.  

Hopefully, she's learned her lesson. But it's going to take a pretty brave woman to volunteer for the role of Denise Richards' new best friend.