Where She Went by Gayle Forman
This is the sequel to If I Stay, a very powerful novel by Forman. In the frst book, Mia is in a tragic accident that takes the lives of her father, mother, and younger brother. Mia herself is left in a coma. As she fights for her life, Mia's byfriend and rising rock star, Adam, is by her side begging her to stay. Mia narrates, trying to decide whether to fight to stay alive or join her family.
Where She Went picks up about three years later and is told by Adam. He is a world famous rock star. Has a gorgeous actress girlfriend, house in LA, more money than he can use, and fans around the world. Yet, Adam is miserable. He doesn't know what happened between him and Mia. Why did she leave him?
Where She Went tells Adam's story of his rise to fame, what happened to Mia in that time frame, and what exactly drove them apart as they both try to regain their lives.