Por-nei-a is a made up term that the Washtowel Babble and Crap Slaveholdery uses to disfellowship people while extracting embarrassing details about people's private lives. And, it is totally unnecessary.
As I see it, it is none of anyone's business except the parties involved. In the case where one or both parties is married to someone not involved, it is also the innocent spouse's business. If a child is forced or scammed into getting involved, we now have an infraction that goes beyond simple fornication--now, it becomes an initiatory force, threat of force, and/or fraud issue and is much more serious. (Which is more common within the Washtowel, with all the pedophiles they have on the loose).