I was completing quests for the Vampires at Castle Volkihar and took a quest to turn my wife, Ysolda, into a Vampire like myself. I did and she thanked me the next day. Now a couple of days have passed and I've come back to my house to find that she's gone. I remember the Vampire I did the quest for said that she was now "part of the family" but I searched the castle and she wasn't there either. I'd very much like to find her, but have no idea where she could have gone.