Upon the Riven Throne by Melissa Wright

The prince of Rivenwilde is about to meet his match.
It is a truth universally acknowledged that a cursed prince must be in want of a wife… to break his curse. But when a princess on the run bargains her way into his palace, he discovers he’s not the only one who guards a secret.

Princess Mireille is in trouble.
Her kingdom is under siege by a cruel and powerful fae, and Mireille’s only chance to save it lies beyond the filigree wall, in the kingdom of another fae. The prince of Rivenwilde vows to protect her and their deal is struck, but the bargain only buys Mireille one month. At the turn of the moon, she must become his bride or his prisoner.

Prince Alder is prickly at best.
Between dark and ancient secrets, meddling palace staff, and vicious fae courtiers, a princess would be hard-pressed to win him over. But he wants nothing more than to break the curse that binds him, and Mireille might be the only way to see it done.

Grumpy x Sunshine. Forced Proximity. Fae Curse. Upon the Riven Throne is the final title in the now complete Rivenwilde gaslamp fantasy series (blending magical and historical), but each can be read as a standalone.