I have often wondered myself why she didn't just take off and leave when she had the chance.
I think it's because this story sounded a lot better in her head than it did when it came out of her mouth.
Or because she is so far gone mentally that she actually convinced herself that she has no reason to run as what she was going to tell them was the truth.
Or she was just plain scared and thought that she could make it all go away, just like it always goes away with Mommy and Daddy when she gets in trouble.
JMO. Unless there's a link, I can't prove it.