Chasing Tomorrow

Why couldn't it be a happy ending?!

I couldn't understand the whole thing of becoming straight and starting a new life. Beginning of the book Tracy wants to stay a con-artist, she's bored of living a decent life and Jeff is totally involved in the museum and turning over a new leaf. But at the end of the book, Tracy doesn't want to be with Jeff coz he went back to his old ways (like she had wanted him to) and she was now happy being a mother and home-maker (which she totally hated and was bored of) -_-