Blue Lily, Lily Blue by Maggie Stiefvater

blueBlue Sargent has found things. For the first time in her life, she has friends she can trust, a group to which she can belong. The Raven Boys have taken her in as one of their own. Their problems have become hers, and her problems have become theirs. The trick with found things though, is how easily they can be lost. (Book 3 of the Raven Cycle. Book 4 to be released  in 2015, the official release date has not yet been released)