Wow, both of these books are just great!

Where She Went  - Gayle Forman

The second book in the series happens three years after Mia's car accident, and is narrated from Adam's perspective.  Things have changed for Adam and Mia.  A LOT.  Shooting Star hit the big time, making Adam a huge rock star.  Mia moved to New York to go to Julliard.  And just stopped talking to Adam.  He's tormented by her silence, wondering why she left, when all he wanted was to be with her.  He happens to be in New York with Shooting Star when he sees that Mia is giving a recital.  On the spur of the moment, he gets a ticket to her show.  She finds out he's in the audience and calls him backstage to begin their first meeting in three years.  The emotional journey that happens next is amazing.

I stayed up ridiculously late reading this book in one sitting.  It's that good.  I just didn't want to put it down before I found out what happened with Adam and Mia.