Jodie foster just authored an op-ed piece, where she defends Kristen Stewart - http://www.thedailybeast.com/articles/2012/08/15/jodie-foster-blasts-kristen-stewart-robert-pattinson-break-up-spectacle.html
I understand Jodie Foster's points, and I've long believed that thrusting children into the "fame" thing is asking for a messed up child.
But, did Kristen do anything between Panic Room and Twilight? Probably, but I don't know about it.
Her current predicament isn't because she was thrust into the spotlight at a young age.
It's because she is incapable of having a mature relationship, and believes to "love the one you're with." She ended a long-term relationship with another actor after getting together with Pattinson during filming of Twilight. Now that Twilight is over, Rob can't do anything for her, so she decided to sleep with a director who could help her get future roles.
I've LONG believed that as soon as BD2 was released, RobStew would be over.
Should her cheating have been private, maybe so, but if you're going to make out in public and in a car in public, you can't expect it not to be seen and consumed.