All characters from the Yogo family have this Disadvantage. Characters with the Yogo Curse will betray the person they love the most, once in life. Some action, either intentional or unintentional, will cause that person pain. The more it is tried to avoid it, the more painful the betrayal will be. 
Members of the Asako family are closely related to the Yogo, so some members of the Asako family occasionally pop up with the terrible affliction.