Broken Halo (Fallen Angels #1)
Zoey Marcel

Despite the fact that Sonya watches over human souls and Nimbus seeks to ruin them, neither one has ever stopped loving each other. But angels and demons are forbidden to mate. Frustrated that Sonya resists his wiles despite her obvious need for him, Nimbus employs his soul devourer friend, Jude, to help him trick the dark-haired beauty into losing her soul.
Devastated that her compassion was used against her, Sonya finds herself trapped in a world of demons and vampires where humans are made into sex submissives and reduced to little more than objects. She teeters back and forth between reluctance and acceptance, between resentment and lust.