It's wrong to have intimate relations with someone else's partner.
Victor is at a bar and is propositioned for sex by a woman whose husband is on a business trip.
Victor wants to respond to the proposition.
Victor turns down the proposition on the account that the woman is married.
Victor accepts the proposition and has sex with the woman.
Victor leads a sex life that isn't complicated.
Victor is entangled in an affair where the husband may be angry with him.