Nicole Richie is reportedly furious over boyfriend Joel Madden’s friendship with actress Mary-Kate Olsen. So much so in fact, the socialiate has ordered theGood Charlotte rocker Madden to keep away from MK after she was seen flirting with him at a recent dinner and fawning over him on a tour bus in New York just days later.

“Nicole exploded at Joel and demanded that they leave the party. Afterward, Nicole warned him to stay away from Mary-Kate,” a Star Magazine insider has revealed.

“Nicole’s really suspicious of what happened between Joel and Mary-Kate,” the spy adds. “She’s been friends with Mary-Kate for a while, but she doesn’t trust her at all when it comes to Joel. Nicole is really angry right now and has made it very clear to Mary-Kate to stay far away from her man!”

Joel’s relationship is described as one of compassion in which the musician sees himself as a big brother to the pint-sized Olsen, who is 22.

“If Joel would just marry her, she wouldn’t be so jealous abouti Mary-Kate. But despite having a baby with her, it doesn’t look like Joel’s going to truly settle down with Nicole any time soon.”