I'm curious...if someone is not legally married and common law is not the law in that person's state but they live together(for a very long time) in a supposedly monogamous relationship masquerading as "fiancées" would it not be considered an affair if one person cheats on the other one? I know it's certainly considered "cheating" but is it an "affair" if you aren't legally married? With so many people choosing to live together without marrying...it's cerainly a valid question!