Nicole Richie to Joel Madden: Stay Away from Mary-Kate, Or Else!

Could this be a Battle of the Pint-Sized Socialites? Things may come to a blow between Nicole Richie and Mary-Kate Olsen if the mini-mogul doesn't back off of Nicole's boyfriend, Joel Madden.

After hearing that Mary-Kate was flirting with Joel at a recent dinner, Nicole is reportedly making demands that Joel keep his distance from her.

A source told Life & Style, "during the dinner, Mary-Kate was very playful with Joel. It was all fun and games, but with the Olsens nothing is as simple as that. Nicole exploded at Joel and demanded that they leave the party. Afterward, Nicole warned him to stay away from Mary-Kate."

Apparently, the dinner-time flirting wasn't the first encounter between Joel and Mary-Kate, who have a history of exchanging not-so-innocent sweet nothings. As recently as last week, Mary-Kate went to a Good Charlotte show, and hung out backstage with Joel afterwards.

The source adds, "After the concert, Joel invited her back to see the tour bus. He showed her some baby photos of Harlow. Joel isn't one to lie or hide things from Nicole, so the next day he told her about it on the phone."

Guess who didn't take this well? "Nicole freaked out. Joel thought she'd respect the fact that he was trying to be honest—after all, he and Mary-Kate are just friends—but Nicole was hurt and angry. He couldn't deal with it, so he hung up, and she kept texting him after that," the spy says.

Could this mean the couple's wedding date will be pushed even further off? Perhaps not, according to a source close to the couple. "They're having their usual ups and downs. I think they're madly in love and want to get married. But I also think it's moments like this that will continue to keep their wedding on hold."

Yes, jealousy is surefire ways to keep your man from popping the question. But seeing how crazy in love Joel is with Nicole, we have a feeling a little neediness isn't going to keep them from walking down the aisle. Just as long as Mary-Kate Olsen stays far, far away from the church...