Fallen (and all its sequels) by Kate Lauren - QAM

Info:
Fallen is a 2009 young adult gothic fantasy and romance novel written by Lauren Kate. The novel revolves around a young girl named Lucinda "Luce" Price who is sent to Sword & Cross Reform School in Savannah, Georgia, after she is accused of murdering a boy by starting a fire. At the reform school, she meets Daniel, a handsome boy whom she feels inexplicably drawn to, and believes she has met before. The book revolves mostly around the love triangle between Luce, Daniel, and Cam, who is another boy enrolled at Sword and Cross.

Read more at: http://en.wikipedia.org/wiki/Fallen_%28Kate_novel%29

Full Series:
Fallen
Torment
Passion
Fallen in Love
Rapture