Treason and Reason

"I have tried to do my duty."
"Ye have striven to admiration."
"I sentenced her because it was the law to sentence her. I have done my best to see the sentence will be carried out."
"But it willna be. Lancelot will bring her safe."
"Gawaine, you are not to think that I am trying to get her rescued. I am the justice of England, and it is our business now to burn her to the death, without remorse."

Gawaine's first line really hits it on the head here, whether Arthur is willing to admit it or not. We see Arthur's admiration cloud his judgement multiple times throughout the passage. It's accepted that he knows about the affair, but keeps it hushed for the greater good of the kingdom. That's why he isn't surprised when the brothers and Mordred bring it up to him. Many before him have brought it to his attention, all to be killed by Lancelot in combat. I also love that killing your opponent holds legal weight, and the victor is the one considered to be just and right. It's like if Evander Holyfield led OJ's defense team. It almost seems to me that Arthur is accepting of the affair because of the great deal of love that he has for Guinevere and Lancelot. That's why he opposes trapping them. Because of the love and respect he has for them, he can't, in good conscience, do what he thinks will be deceiving them, even though they've been doing that to him for years. This is also weird logic coming from a man who put an entire boat full of babies to death just to save himself from the wrath of his son.