Kristen Stewart 'cheats on Robert Pattinson with married Snow White And The Huntsman director Rupert Sanders

Kristen Stewart has cheated on Robert Pattinson with a married filmmaker twice her age, it has been claimed.

The Twilight actress, 22, is said to have fallen for the charms of Snow White And The Huntsman director, Rupert Sanders, 41.

As Kristen prepared to spread her wings from the vampire franchise, she joined forces with the father-of-two to work on his $170m feature debut - which was released just last month

But despite the film long since wrapping, it has been reported that just last Tuesday, Kristen was caught in the arms of Rupert - with Us Weekly claiming to have photographic evidence

Kristen and Robert were hailed as the perfect couple, in love both on and off screen.

However, it seems not even they are immune to the perils of infidelity claims

According to a source, Kristen and Rupert, who is married to British Vogue model Liberty Ross - were caught in a romantic clinch and it seemed like 'they couldn't get enough'.

And an insider 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.