I think adultery should be treated as some manner of tort, personally. I don't think most of the adultery laws that are currently on the books in states that still have them are very practical or well-considered. I doubt Virginia is an exception.
Seriously? That seems completely crazy.
In a way it already is. Usually if you're divorcing your spouse because they were unfaithful you can get something out of it, or at least better terms than if no adultery had taken place.
The key difference being that one would be able to sue the person your spouse slept with. If the state recognizes marriages, it does so because a marriage is believed to have value worth protecting by the state, so I don't see how treating adultery as a tort is such a crazy idea.