Dark Elements by Jennifer L. Armentrout
Prequel:
Wardens, gargoyles and demon hunters at night, are very protective of their women. Which is the reason Jasmine is put in a golden cage with all the other girls - a cage she flees from whenever she has the choice. When her long-lost love returns to marry her, she sees her choice.
Series:
Layla would love to be protected like the Warden girls. But she is different. An outcast. Hated, even. Growing up at a race that was created to hunt demons sucks when your mother a demon. Layla hates her hertiage – especially since she can not get close to a person without taking his or her soul – and thus sending it to hell. Directly. Which would make any relationship impossible, especially not with a Warden like Zayne, with his pure, so very tempting soul. Any relationship... Except for one with a demon. When the crown prince of Hell comes into Layla's life, he turns her world upside down: Because she has to see that demons are necessary, but the people with the purest souls can be capable of the greatest evil. And, of all the people, Roth's supposed to keep her alive when all the races and even her family start gunning for her. But what if Layla's death is actually the only thing that can keep the apocalypse at bay? Quite simple: In this case, she has to die.