Ed Westwick is either cheating on Chace Crawford or the co-stars really aren't dating. Westwick has been busted making out with Drew Barrymore all over Manhattan.

Barrymore, 33, and Westwick, 21, reportedly partied together till 6 a.m. after leaving the Saturday Night Live after-party this weekend.

"They were definitely all over each other," a source told US Weekly. "It was on."

Ed and Drew popped up together again on Tuesday night at a Kings of Leon gig at Webster Hall, where they indulged in what a witness called "a full-on make-out session" before partying the night away at Bowery Electric.

That's too bad, I thought Chase and Ed were a cute couple. There were also rumors that Barrymore was smooching Crawford on Saturday night too. A couple that plays together, stays together I guess!