The Six Rules of Maybe, by Deb Caletti.
I made a silent promise to myself - I would come back when no one was here, and I would read those words. Maybe at that moment I knew what a thief must feel, a jewel thief. The way his heart would quicken with need and envy and want when he gazed down at the promise of diamonds and rubies. The way he knew he would soon hold them in his hands, pretending they were his even if they could never be.
I have read a few other Deb Caletti books and they were all great, including this one. Scarlet's older sister Juliet has returned home not only pregnant, but with a new husband as well. They decide to stay with Scarlet and her mother until the baby is born, but of course there are complications.
4 stars out of 5.