Hidden Desire by Lila Fox

Fedosian winters are cold, but colder still are lovers turned strangers.
As autumn turns and winter settles over Fedosia, cold has seeped in between Sofia and Aleksei. She loves him still, but the archmage’s memory spell has made her a stranger in his eyes. They hardly speak anymore, and their troubles only compound when they arrive in Sarostia and discover Duke Rodion of the Red Den has his own ambitions for the throne. He desires war—and not just with the Guards.