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Britney Spears' boyfriend is no womanizer. Multiple sources are slamming a recent tabloid claim that Spears' beau Jason Trawick cheated on the singer at L.A. club Roger Room Dec. 30 -- including Milana Rabkin, one of the women spotted with Trawick on the night in question.

A source explains to that the Dec. 30 gathering at Roger Room was a birthday party for "one of Jason's bosses" at WME, the Hollywood agency that employs Trawick. "I used to work at WME. It was my old boss' birthday and we were all hanging out," Milana Rabkin, 22, tells exclusively. She and Trawick, she says, "worked together" recently. "We send him scripts," says Rabkin who now works  at Energy Entertainment. That night at Roger Room, she and a friend joined Trawick and a married male WME colleague to talk shop.

Rabkin says she and Trawick discussed a screenplay for a potential film; "we had actually sent [the script] to him to read for Taylor Swift," she adds. "We were hanging out and catching up on that. It was purely professional."

Around 1:45 a.m., the foursome left for the Standard hotel. "We were hungry, and I really wanted to talk to Jason about the script," Rabkin explains.

"They did go to the Standard," the source confirms. "The girls and Jason's friend had food. Jason didn't. Jason then left and went home."

Trawick and Spears, 28, have been dating since spring of 2009. Pals have told Us Weekly that the Hollywood agent has stood by the pop star in her darkest days, and has become close with her two sons. "[Britney] has been honest with Jason about what she’s been through in a way that I don't think she's been with other people, and he always preferred to not sugarcoat the harsh reality of what happened to her," says a friend. "He tells her when she should take responsibility for her own actions."