Robert Pattinson and Kristen Stewart have reunited for a month's "trial".

Related: Pattinson wants to marry Kristen Stewart

The couple split during the summer when it was revealed Kristen had been cheating on Robert with her married 'Snow White And The Huntsman' director Rupert Sanders but are now trying to get their romance back on track, though the British actor is still unsure he can forgive his girlfriend's behaviour.

Related: Robert Pattinson takes back Kristen

A source said: "Robert has had a lot of time to reflect on what has happened and, while he may still be hurting, he has also come to realise just how important Kristen is to him.

"He has warned Kristen that he might never be able to forgive and forget. But he's agreed to give it a month to see if they can make it work. If they can't he says he will walk away."

Though the pair are no longer living together, they meet up regularly but Robert has laid down some ground rules.

The insider explained to Britain's Grazia magazine: "Kristen hasn't stayed over at Rob's new place yet. They have seen each other most days since their initial meeting but they are taking baby steps.

"He has also requested they don't talk about Rupert or what happened.

"Of course Kristen is ecstatic to have Robert back. But she is still on edge because she knows it is only a trial and Robert could change his mind. She says she feels like she is walking on eggshells."