The Frostbound Queen by Amy Pennza

Keep the cold. I’ve always understood my duty. As heir to the Winter Court, I must be ready to take my father’s place and keep the realm safe under a blanket of frost. But my father never taught me how to protect my people. That role has fallen to his best friend, Ronan, who agreed to serve as my guardian after my father grew ill. Charming and dangerous, Ronan hasn’t let illegitimacy or family tragedy stop his rise to power. A master of the elements, he’s a faithful ally.
Until my father dies.
Pushed from the throne, I run to the one place Ronan won’t venture. Crossing into the human lands will weaken my magic, but I need new allies. I find one in Sigurn Brighthelm, the dark-eyed rebel Prince of Nordlinga. Sigurn is no stranger to power. But as I discover too late, he’s no stranger to Ronan, either.
Now I’m caught between two men with conflicting desires. As battle lines are drawn and secrets are revealed, I’m determined to claim my crown. My freedom—and my kingdom—hang in the balance. But as passions heat up, I’m not sure the ice I’ve built around my heart can endure.

Because ice doesn’t always thaw. Sometimes, it shatters.