Ed Westwick is "devastated" after learning his girlfriend was allegedly dating other guys behind his back.

The 'Gossip Girl' hunk has ended his two-year relationship with co-star Jessica Szohr after discovering she was seeing other guys, including a close friend of the actor.

A source said: "Ed discovered that not only was Jessica seeing a close friend of his - he was told about it personally, by the guy - but that she was also seeing a few other men."

Jessica, 25, reportedly turned to other guys for attention whenever Ed - who has recently been in Germany filming new movie 'Chalet Girl' - wasn't out with her.

The source added to the New York Daily News newspaper: "When Ed wasn't out with her for the night, she'd flirt heavily with guys. It was only a matter of time before it got back to Ed."

News of the couple's split has come as a shock to many, including Ed's close friend and co-star Chace Crawford.

The insider said: "Chace Crawford is good friends with both of them and had no idea. He thought they were the perfect couple."

Although Jessica has denied the claims, friends insist she is trying to put on a brave face as is hopeful her relationship can be salvaged.

One pal said: "Jessica is hoping she can convince Ed to get back together. She keeps denying the rumours that they broke up, because she doesn't even want to believe it's true. She's really chasing him."

However, it seems she will have to try hard to win back Ed.

The source added: "He wants nothing to do with her right now."