(The Fallen Trilogy) Fallen

Eighteen year old Lena Gold, was just a normal teenage girl, like everyone else, however, her world is turned upside down when she falls in love with a demon, of the Kareo bloodline, a line of powerful demons, who've remained number one, for centuries. Though when he breaks her heart, and she is forced to move past everything, she learns that the darkness surrounding her, has been pretty busy during their time apart.
With the help of a few friends, she unmistakably opens up doors, she now wishes were never opened, when she learns the impossible truth behind her mortal heritage.