In marital relationships, exclusivity expectations are commonly assumed although they are not always met.
When they are not met, research has found that psychological damage can occur, including feelings of rage and betrayal, lowering of sexual and personal confidence, and damage to self-image.
Such covertly illegitimate children amount to about 1–2% of newborns in European populations.
“So when he sat me down one day to tell me he was a sex addict, I actually laughed – although I soon stopped when he disclosed night upon night of watching pornography for hours on end and numerous short-lived affairs.
My life fell apart.” Sex addiction hurts partners in a way that no other addiction can, says Paula Hall, who has written a book on the subject.
Women usually feel more threatened by the emotional betrayal of a partner’s online affair, while men are more concerned about physical encounters, Hertlein says, but the gender differences are lessening.
“That is starting to even out in part because of the equality of opportunity that the Internet brings to everybody,” she says.