Rachel Bilson and Adam Brody Done?

Rachel Bilson and Adam Brody, who play a couple on The O.C. and have also dated off-screen since 2004, have decided to call it quits reports Life & Style .

"They've been done for a few weeks," a friend close to the couple tells Life & Style. "They are just done. That's all there is to it. There's no drama. They just ended it."

That may explain why Adam showed up solo to a party on Nov. 28 for the US premiere of Volkswagen's concept car Tiguan in LA.

"He was definitely acting like a single guy," an eyewitness tells Life & Style.

"He's a girlfriend type," one source tells US Weekly of Brody, . Adds another source, "He never flirts but is super nice to anyone who approaches him."

According to nightlife insiders in LA, he's been spending a lot of time without Rachel at the clubs with his guy friends.

In September , Star magazine reported that Adam Brody and Rachel Bilson, were having some trouble and that Bilson's The Last Kiss co-star, Zach Braff was part of the problem.

An insider told Star that even though it 'looked like [Rachel and Adam] were on their way to getting engaged just a little while back,' they are now 'going through a really difficult period right now.'

Star source claimed that Zach Braff and Rachel became close while filming The Last Kiss and 'Zach calls Rachel a lot and they talk on the phone like girlfriends,' reported the insider. "But what really eats away at Adam is when Rachel starts talking about how mature Zach is."