But, according to a recent study by David Ley, Justin Lehmiller and the writer Dan Savage, acting on cuckolding fantasies can be a largely positive experience for many couples, and hardly a sign of weakness.

References to cuckolding appear in literature as early as the 13th century, usually in the form of male characters who fear that their child has been sired by another man during an act of infidelity. Today, however, cuckolding has become fetishized into a powerful sexual fantasy for some men, who get aroused by the idea of their romantic partner engaging in sexual activity with someone else. Women also share this fantasy, but less so than men.

"This fantasy has been around as long as marriage and sexuality," said Ley, whose book "Insatiable Wives" addresses cuckolding in heterosexual couples. "But we're hearing more and more about it these days, and more people are rejecting the social stigma against this fantasy."