So we should all do it and say affairs are wonderful and getting divorced tremendous.
And this is why you can't have an intelligent conversation about this with some people.
Nobody has said affairs are wonderful and getting divorced is tremendous. We are saying that having an affair isn't an impediment to being head of the C of E, as evidenced by the fact that a serial and open adulterer founded it. Most of us would also say it's better to get divorced if you're both absolutely miserable, as C & D were.
And while ideally C & C would not have had an affair, the fact remains that Charles and Diana were a terrible match, both unfaithful, both unhappy, and Camilla has now been married to him longer than Diana was. It's clearly the better relationship.
It's not condoning the affair to say that there's nothing to gain by attempting to rewrite the laws of marriage and monarchy in an attempt to punish them for it 40 years later. They were free to marry, they married, the rule is that a king's wife is queen. It's not personal, it's not a comment on their private lives, it's just the law.