Books like Begin Again by Mona Kasten

For Kayden, suffering in silence was the only way to survive. If he was lucky he could keep his head down, do as he was told and make it through the day. But one night it seemed like his luck and his life might finally end until an angel named Callie appeared just in time to rescue him. Callie has never believed in luck. Not since her twelfth birthday when everything was taken from her. After the worst was over she locked up her feelings and vowed never to tell anyone what happened. Now six years later she continues to struggle with the painful secret that threatens to consume her. When fate lands Kayden and Callie at the same college Kayden is determined to get to know the beautiful girl who changed his destiny. Quiet and reserved Callie still fears letting anyone else into her world. But Kayden is certain that Callie has come back into his life for a reason. And the more he tries to be a part of her lifethe more he realizes that, this time its Callie who needs to be saved .

Every day in chemistry class, high school student and aspiring songwriter Lily Abbott is finding notes left to her by a mystery boy, love letters really, and she hopes they are from Lucas, a boy she is attracted to--so when she finds out they are really from, she is shocked and unsure about how to respond.