Renesmee,
It's all lies; they were never even going out in the first place. The media makes this up just to hype up all of the teenage girls, so Kristen and Robert probably got made, making the media say they 'broke up', whether they were together or not. And even if they were together, it wouldn't of lasted, Robert is to flirty and would have cheated, and that's what makes the 'cheated with another costar' thing in all the magazines seem believable, even though it's all a sham.
the vampire with a beating heart