The Sundered Blade by Kenley Davidson

War is coming…
… and Prince Vaniell is willing to do whatever is necessary to protect the Five Thrones. He’ll even entrust his life to a former enemy as he attempts to gather allies against the looming threat of Garimore’s armies. From Iria and Eddris to the distant mountains of Farhall, he’ll risk everything to bring the Thrones together, desperate to save Abreia from the cruel realities of war.
But he must do it without Karreya. Her mission is to infiltrate Hanselm, the capital city of Garimore, and confront the man she knows as Father. It is a daring gamble that hinges on his own pride and ambition, and Karreya believes she can provoke him into acting before he is ready.
But nothing could have prepared her for seeing her father again—for the secrets that would come to light, or the truths she would discover about herself. When her hopes and plans lie in ruins, she must decide just how much she is willing to sacrifice, and how far she’s willing to go to protect the gray-eyed mage prince she has come to love.
Armies are on the move, and under the shadow of dragons’ wings, the Five Thrones wait to learn whose hand will direct their future. Will the tyrant, Melger, fall? Or will Vaniell and Karreya fail in their quest to save the ones they love?
Bonds will be tested. Hearts will be broken. And by the choices of a destined few, the fate of the world will be forever changed.