The Rose and the Dagger by Renée Ahdieh

The darker the sky, the brighter the stars.

In a land on the brink of war, Shahrzad is forced from the arms of her beloved husband, the Caliph of Khorasan. She once thought Khalid a monster—a merciless killer of wives, responsible for immeasurable heartache and pain—but as she unraveled his secrets, she found instead an extraordinary man and a love she could not deny. Still, a curse threatens to keep Shazi and Khalid apart forever.

Now she’s reunited with her family, who have found refuge in the desert, where a deadly force is gathering against Khalid—a force set on destroying his empire and commanded by Shazi’s spurned childhood sweetheart. Trapped between loyalties to those she loves, the only thing Shazi can do is act. Using the burgeoning magic within her as a guide, she strikes out on her own to end both this terrible curse and the brewing war once and for all. But to do it, she must evade enemies of her own to stay alive.