Gabriele D’Annunzio 
Intruder 

The Intruder (Italian: L’Innocente) is an 1892 novel by the Italian writer Gabriele D’Annunzio. It is known as The Victim in the United States. It tells the story of the dandy Tullio Hermil who is habitually unfaithful to his patient and loving wife Giuliana, until the wife eventually does the same and becomes pregnant with another man’s child. (Excerpt from Wikipedia)