To The Gallows by Elizabeth Skarpnes

When Lorali Wynmar oversees the last blessing of Athera’s most wanted criminal before he is hung from the gallows, she receives a surprising command from a dark deity: save him. With the noose tightening around his neck, she invokes the forgotten rite of a gallows marriage to free him from his fate.
For the next year, Eldric Lorecaster is now bound to the enigmatic high cleric that saved him. Forced to live together under the constraints of their bond, the pair forge a tentative and unlikely friendship.

When their pasts collide, they must choose if they will follow their predestined-paths or diverge and grow towards something new.