It's hard, being the fastest girl in the world.
She just wants control over her life, but it feels like it's moving even faster than she can, slipping through her grasping fingers. The loss of control leads to resentment, and she takes it out on those she loves most. It's not fair. It's a terrible way to react, but she can't seem to stop, which only increases the self hate, and need to cope. It's a vicious cycle, and she feels entirely trapped in it. No one understands her motivations. Everyone must think she's a superficial jerk.
Maybe she is.