We're really not supposed to have affairs. It doesn't work that way. The primary problem with affairs is that the people who have them never seem to stop with just one. I can understand, if there's really no venue (court) then they have to just personally between themselves go ahead and agree, we're together, in love married, kids. There haven't always been nations. There was no Israel when Joseph was sold into Egypt, there weren't even ten commandments, so how could there have been? But if you and that person get in bed and have an affair, warning, God knows about that. God probably even thinks you're married and owe each other a relationship, if you two carry it on long enough.