Frozen Dawn by Kathryn Ann Kingsley

Her people murdered his family. He vowed to destroy them. But now, a curse binds them together.

Life in the far northern reaches of the Dominion is unkind, and life under the reign of Morten, the dreaded ruler of the North Wind, is worse. As the last outpost of those who worship the Old Gods is destroyed, Dawn and her sworn enemy come face to face, and she learns there is more that’s frozen in the north than just the weather.
Many centuries have passed since Morten vowed destroy all traces of the people who murdered his family, even if it meant reshaping the world to do so. But when he stands poised to do just that, he learns the curse he suffers still holds secrets, even after so long.
Dawn is now the prisoner of the undead and seemingly unstoppable Morten. But the gods marked her for a purpose—binding her fate together with that of the North Wind.
Is she meant to thaw his heart…or tear it from his chest?