She escaped from the house, and left a note for Marcy:
"I thought ... you were trying to make me choose you then I saw that Ben chose me. He picked me out and he made me his. And there is no unchoosing that... It's time for me to grow up for good, and have something that's mine, and mine only..."
And then she's eyeing a little girl in the park.
Yes I thought this was a very weird way to end the story. While somewhat understandable (I mean, the most sane person she knew was the one who picked her out from a park - her own mother was a nutjob), it's still a very creepy ending.
I really wish the movie had portrayed a more normal mother who was helping Leia adjust, rather than someone who turned out to be much worse than the kidnapper seemed to have been. It's no wonder that Leia left and tried to create her own family.