Fake Wastrel, True Archmage EP 5

Betrayed by her sister, Elizabeth weds Darcy, a half-elf scorned as magicless—secretly the grand sage. When demons breach the city and Elizabeth fights for his necklace, Darcy appears on an ancient dragon. He unleashes power to save his wife and crush his foes. The scorned princess becomes Elf Queen, ruling with the Grand Sage to guard the realm.