Kristen Stewart Rob Pattinson Breaking Dawn Pt1 London.jpg *Update: This story has been updated here. 

He may be loved by millions of females across the world but even Robert Pattinson has his own relationship dramas to deal with. The British actor's love life has been rocked by allegations that his girlfriend, Kristen Stewart, cheated on him with a married man twice her age.

Us Weekly has published photos of the 22-year-old actress in the arms of her Snow White and the Huntsman director, Rupert Sanders, 41. Despite wrapping the film months ago, the pair were reportedly caught out by cameras in a romantic embrace just last week. A source has told the magazine that the pair were spotted getting cosy with each other and it seemed like "they couldn't get enough." To make matters worse, Rupert is already married to British Vogue model, Liberty Ross, with whom he has two children.

US Weekly Kristen Stewart cheats

An insider has also told People.com: "Kristen is absolutely devastated. It was a mistake and a complete lapse in judgement. She wasn't having an affair with Rupert. It was just a fleeting moment that shouldn't have happened. She never meant to hurt anyone. She's a good person who just made a bad choice."

Although always fiercely private about their relationship, the news comes just months after the Twilight actor gave an interview to Vanity Fair. "There is one thing I've never understood: Why people cheat. My parents met when my mom was 17 and my father 25, they are still together, and seem very happy. I grew up believing that you can be together all of your life," he said.

Let's hope it isn't what the tabloids say it is!

For more celebrity gossip and news check out our sister blog, Star Trip.

[Sources: Us Weekly / People.com via Daily Mail]