Black City by Elizabeth Richards

A dark and tender post-apocalyptic love story set in the aftermath of a bloody war

In a city where humans and Darklings are now separated by a high wall and tensions between the two races still simmer after a terrible war, sixteen-year-olds Ash Fisher, a half-blood Darkling, and Natalie Buchanan, a human and the daughter of the Emissary, meet and do the unthinkable--they fall in love. Bonded by a mysterious connection that causes Ash's long-dormant heart to beat, Ash and Natalie first deny and then struggle to fight their forbidden feelings for each other, knowing if they're caught, they'll be executed--but their feelings are too strong.

When Ash and Natalie then find themselves at the center of a deadly conspiracy that threatens to pull the humans and Darklings back into war, they must make hard choices that could result in both their deaths.