<p>Robert Pattinson and Kristen Stewart's relationship is in trouble amid claims that the actress cheated on her 'Twilight' co-star with the director of 'Snow White'.<br /><br /></p>.<p>Stewart, 22, is said to have had a brief fling with Rupert Sanders recently. Sanders, 41, directed her in 'Snow white and the Huntsman', the People magazine reported quoting sources.<br /><br />British director is married and has two young children with model Liberty Ross.<br /><br />"Kristen is absolutely devastated. It was a mistake and a complete lapse in judgment. She wasn't having an affair with Rupert. It was just a fleeting moment that shouldn't have happened," a source said.<br /><br />"She never meant to hurt anyone. She's a good person who just made a bad choice," the source added.<br /><br />Stewart and Pattinson, 26, were photographed together just days ago at Comic-Con. The British actor had even hinted about a future marriage.<br /><br />The couple first met on the 'Twilight' set and reports began almost immediately that they were a dating. After being initially coy, they became open about their relationship.<br /><br />The representatives of both Sanders and Stewart were not available for comment.<br />Meanwhile, Us magazine has claimed that they have photographs of Stewart and Sanders together.</p>
<p>Robert Pattinson and Kristen Stewart's relationship is in trouble amid claims that the actress cheated on her 'Twilight' co-star with the director of 'Snow White'.<br /><br /></p>.<p>Stewart, 22, is said to have had a brief fling with Rupert Sanders recently. Sanders, 41, directed her in 'Snow white and the Huntsman', the People magazine reported quoting sources.<br /><br />British director is married and has two young children with model Liberty Ross.<br /><br />"Kristen is absolutely devastated. It was a mistake and a complete lapse in judgment. She wasn't having an affair with Rupert. It was just a fleeting moment that shouldn't have happened," a source said.<br /><br />"She never meant to hurt anyone. She's a good person who just made a bad choice," the source added.<br /><br />Stewart and Pattinson, 26, were photographed together just days ago at Comic-Con. The British actor had even hinted about a future marriage.<br /><br />The couple first met on the 'Twilight' set and reports began almost immediately that they were a dating. After being initially coy, they became open about their relationship.<br /><br />The representatives of both Sanders and Stewart were not available for comment.<br />Meanwhile, Us magazine has claimed that they have photographs of Stewart and Sanders together.</p>