Secrets and Stardust (Celestial Whispers #1) by Jeannin Counts:
 
The stars are not what they seem. So look away; they’ll whisper you your fate.

Iyana’s only ambition in life is to become a healer like her grandmother, but that all changes when her village is attacked by a neighboring kingdom. She desperately calls upon the heavens for salvation and the stars respond, yet not as she had ever imagined. She is sent Altair, a hypnotically handsome star in human form. Iyana is more shocked to discover that she is an Aztia, a magic bearer born once in every generation, and that a captured enemy soldier named Emmeric is unwittingly caught up in her destiny.

Although he is fated to work with Iyana, Emmeric is reluctant to assist a woman from the village he was recently trying to destroy, no matter how spellbinding her beauty is. He trusts his rival Altair even less, as the star and Iyana are caught in each other’s orbit.

When the emperor’s own son, Zane, joins their quest to stop his father’s tyrannical invasion, the companions begin unveiling long-buried secrets that echo through time. Secrets that could change the course of human history and reveal the hidden origin of the Aztia themselves.

A captured foe. A fallen star. A forsaken prince.
Betrayal is inevitable. But who will perpetrate it?