Did Kristen Stewart Cheat On Robert Pattinson?

Are Kristen Stewart and Robert Pattinson having serious relationship woes?

According to multiple reports, the actress allegedly cheated on her "Twilight Saga" co-star with her "Snow White and the Huntsman" director Rupert Sanders.

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"Kristen is absolutely devastated," a People source claimed. "It was a mistake and a complete lapse in judgment."

The source claims the alleged hookup with the actress, 22, and the director, 41, took place recently.

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"She wasn't having an affair with Rupert. It was just a fleeting moment that shouldn't have happened," the source continued. "She never meant to hurt anyone. She's a good person who just made a bad choice."

Us Weekly also reported the incident, claiming there are photos of Kristen and Rupert - who is married to British Vogue model Liberty Ross, 33 - caught in a makeout session on July 17 in Los Angeles.

Rupert and Liberty have two children together and the model played Kristen's onscreen mother in "Snow White."

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According to E!, just hours before the story broke, Liberty Tweeted, "Wow," and then later deleted her account.

A rep for the director could not be reached when contacted by People and a rep for Kristen had no comment when contacted by the mag.

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-- Jesse Spero

Copyright 2012 by NBC Universal, Inc. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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