Emmy and Oliver by Robin Benway

Emmy and Oliver were written in the stars to be together, in a lot of ways, but things changed entirely when Oliver disappeared one day and didn't come home. Now everyone is trying to adjust since he's been found and returned to his hometown after ten years. Emmy wants to be normal, in control of her own life, but ever since Oliver's disappearance, her parents have had her on a tight leash. And Oliver's found out that everything he's ever known was a lie so now he has to readjust to a life he doesn't even remember and rediscover himself. Things are different and they might not even fit together now.