[Raptor]

I see lots of errors with this view. First of all, you erroneously define fonrication as,

"Fornication is defined as pre-marital sex which is different than adultery which means sex outside of marriage."

What constitutes fornication is to have s.r. (sexual relations) with a person you are not married to. It´s sex between people that are not married to each other. Each one is commiting the sin of fornication. Obviously pre-marital sex is fornication, but that is just one way or type of fornication. If you introduce this idea of "pre-", the element of time, you just confuse the matter, and will apply it wrongly.

Let´s say someone has been married for 20 years, then the spouse dies. Later, the remaining one has s.r. with someone he´s not married to. That´s fornication, because they had s.r. and are not married.

Let´s say someone is married for 10 years. He has s.r. with someone other than his spouse. That´s fornication, because they are not married. Each one is commiting the sin of fornication. And in addition since he is married to his spouse, it is adultery. He commits both fornication and adultery. He commits fornication with "the other" (because he is not married to her), and in addtion, adultery against his spouse (because he is married to her and was unfaithful).

Adultery includes fornication. Adultery is worse than fornication alone. So obviously, if you are married and you commit fornication, you are commiting adultery. So everyone that is married and commits fornication is commiting adultery. And everyone that is married and commits adultery commits fornication. But not everybody that commits fornication commits adultery.