After she stayed, she went. The second book in the book-turned-movie best seller If I Stay, Where She Went was written in the perspective of Adam years after Mia's decision.
I'm recommending the second book and not the first simply because I liked the second book better (besides, you gotta read the first to read the second anyways, and please don't watch the movie to get the plot. there is a crucial part in the book that connects to the sequel, but the movie completely changes it). Both books were emotionally challenging, teaching life lessons one didn't care for and inducing buckets of tears no one needed to make. However, I personally felt that the second book was more emotionally vested.
Here's Adam, trying to figure his life out after he let go of love so that his love would stay. And all his emotions and inner thoughts are so completely unfiltered, it's as if you become him. His life as a rock star without Mia, his life as a boy in love when he meets Mia again, and his life as a man trying to heal his wounds when continuing the love that never stopped.
When I read If I Stay, I thought that it was as good as it was going to get. You can really see the struggle Mia was going through, weighing whether she wanted to stay or not through trying to find the connection between her and her world as she relived every moment. But when I read Where She Went, it wasn't like getting to know a character, it was like becoming a character.
Both books were beautifully written and jammed packed with stories of a person's life as each tries to make decisions to better his and her life. If you just watched the movie, go read the books! You won't regret it.
So if you're looking for a new read, pick up this book from a local library! I swear you'll love me for recommending this book.