Beast of Mine by Marian Tee

Two years ago, werewolf princess Estrella Moretti received a letter from the one and only man she had ever loved. In this letter, Fae prince Lysander Allard asked for her hand in marriage…and for her to keep his kingdom safe while he sought to conquer an ancient beast.
When Lysander came back, he was no longer man nor Fae. He was something monstrously different, and yet instead of running away in fear or disgust, his young and beautiful wife only looked at him with love in her eyes.
Estrella was every man’s dream come true. It was just too bad that everything was a mistake, and the letter she received…had been intended for someone else.