I know "fornication" is ambiguous, but obviously I meant the category of normalization of adultery. If people agree on no adultery then people agree on no adultery. If adulterers are punished (and false accusers are also punished), then society is delegating to the state a certain power to preserve the good of women not cheating without consequences, and it stays restrained. Society is free not to, and to try to handle it other ways, but I don't know that any other such ways have worked better.