Kristen Stewart is at the center of a cheating report.
The 22-year-old actress reportedly cheated on her "Twilight Saga" co-star and boyfriend Robert Pattinson with Rupert Sanders, the director of her recently released film "Snow White and the Huntsman," according to People magazine.
The magazine's story quotes an unnamed source who claims that Stewart and Sanders had a brief fling and that the young star is "devastated" by her "complete lapse in judgment."
The report also claims that the fling happened recently. Sanders is married to model Liberty Ross, the sister of Oscar-winning composer Atticus Ross. The couple has two children. Sanders, who is English, started out directing commercials. "Snow White and the Huntsman" is his first feature film.
"She never meant to hurt anyone. She's a good person who just made a bad choice," the source told the magazine.
Meanwhile, Us Weekly claims to have photos of Stewart and Sanders together and the story is the cover of the magazine's latest issue.
Spokespeople for Stewart had no immediate comment when asked about the story by OnTheRedCarpet.com on July 24.
Both Stewart and Pattinson recently appeared together at Comic-Con in San Deigo in mid-July for a "Twilight Saga" event. The couple have been seen getting cozy at red carpet premieres and have been rumored to be dating since the first film in the series.
"Twilight: Breaking Dawn - Part 2," the final installment in the hit vampire romance saga, hits theaters on November 16. Stewart's character, Bella, is a vampire, having been turned into one by her husband Edward, played by Pattinson, to save her life after she gives birth to their daughter, Renesmee.
Back in May, Sanders spoke to OnTheRedCarpet.com about casting Stewart to play Snow White in "Snow White and the Huntsman."
"We looked at a lot of people who weren't known and then we started meeting more known actors," Sanders told OnTheRedCarpet.com host Rachel Smith, regarding the casting of Stewart. "I think when we met Kristen, we all just looked at each other and went, 'This is the girl,' because obviously, when you're looking at performances, you're looking at a performance, not the person."