The Alpha King's Stolen Bride

The Bride has a fated mate, and her sister is set to marry the Alpha King, the one the packs are most afraid of. The mate and the sister run off together instead. To protect her pack, the Bride agrees to marry the Alpha King in her sister's place. Her former mate is never told about the switch and goes on believing she is his bride. The two weddings are held at the same time. She is about to leave for good when her former mate works out what happened, and he takes her from the Alpha King to try to get her back. By that point she and the Alpha King have become true mates and her heart is already with him.