Rumor has it that Chris Brown has threatened Ashton Kutcher — telling him to stay away from his ex, Rihanna. According to Star Magazine, a source close to Rihanna said that she’s been seeing Chris while dating Ashton The source said, “He warned Ashton via their mutual friend, Diddy, to keep his distance from her. At first, Ashton took it as a joke – but Diddy told him that Chris was dead serious and really worked up about the idea that Rihanna has moved on.” The source continued, “It’s the last thing he needs. And now Rihanna thinks that Ashton should cut off all contact with her because of Chris’ interference, which she thinks is absolutely what he wants.”Rihanna was reportedly angry that Chris reached out to Ashton and has called him and told him to back off. The source continued, “This fling with Ashton is a way for her to forget about wanting Chris back. Even though Rihanna has publicly insisted that she’s ‘happy and single,’ she’s not going to let anyone spoil this for her.” In related news, more rumors are swirling that Rihanna and Chris will perform “Birthday Cake” and “Turn Up The Music” together in Australia this weekend.