I am certain that plenty of readers out there have had undesirable relationships in the past which they would rather forget. In 'The Daemon Lover' we hear-tell of a woman (a wife and a mother no less) whose former lover returns to claim her.
At first she vows to stand by her family but, upon hearing of her former lover's riches she decides to leave her husband and two young children to run off with him. This is a choice she will regret when she discovers that her lover is not quite what he seems - he is the devil in another guise. This disloyal woman pays dearly for her greed.