Infidelity is a violation of a couple's emotional and/or sexual exclusivity that commonly results in feelings of anger, sexual jealousy, and rivalry.
Venus and Mars Surprised by Vulcan, by Alessandro Varotari. In ancient Roman religion, Vulcan discovers his wife, Venus, having an affair with Mars.
Adultery is extramarital sex that is considered objectionable on social, religious, moral, or legal grounds. Although the sexual activities that constitute adultery vary, as well as the social, religious, and legal consequences, the concept exists in many cultures and shares some similarities in Christianity, Judaism and Islam. Adultery is viewed by many jurisdictions as offensive to public morals, undermining the marriage relationship.
Public punishment of adulterers in Venice, 17th century
Susannah accused of adultery, by Antoine Coypel
Anne Boleyn was found guilty of adultery and treason and executed in 1536. There is controversy among historians as to whether she had actually committed adultery.
Le supplice des adultères, by Jules Arsène Garnier, showing two adulterers being punished