The Light Devoured by Ashley Hintermeyer:
 
A ruthless but alluring Queen forms an unlikely partnership with a mysterious, handsome rebel to save the kingdom she’s callously ruled for three hundred years from the advancing Darkness, a force with powers even greater than her own.

Three hundred years ago, Elayce lost everything to the Darkness.
 
Since then, she has ruled Aerash with an iron fist and her Goddess-blessed magic, determined to strengthen her reign until no one is left standing in her way. Squashing misguided rebellions is nothing new to Elayce, but she falters when she meets a mysterious rebel with an impossibly familiar face.
 
When the Darkness returns to finish what he started, Elayce craves one thing: revenge. But with her kingdom fractured by rebellion and betrayal, Elayce realizes she isn’t strong enough to win the war using her magic alone. She makes a deal with the handsome rebel: she will share pieces of her long-buried past in exchange for his help. But Elayce has been guarded for too long, and if she is not careful, she may give away more than she bargained for–including the chance to save her kingdom.