Justin Timberlake and Mila Kunis
03/14/2011 at 04:00 AM EDT
Just days after Justin Timberlake
and Jessica Biel
announced their split
, there is already speculation that the singer-actor's Friends with Benefits costar
, Mila Kunis
, was the cause of the break-up.
Not true, says a source close to Timberlake, 30.
"Mila had nothing to do with their break-up," the source says. "In fact, no one came between them. They decided their relationship ran its course and it was time to move on."
But now that he is a single man – and Biel, 29, is stepping out
as a single woman – has Timberlake already moved on with Kunis, 28?
"They're not in a relationship," the source says. "They star in a movie called Friends with Benefits
but they're just friends. That's it. They are not together."