When is an insult not really an insult....
When it's an outstanding example of Medieval irony at work; the author does not mince his words when it comes to describing the ugliness of the "hag" before Arthur, and in fact the text seems to labor the point with the detailed descriptions of her outward appearance. However, this is not spite, or an insult, but a statement of fact, because at the time the story was written, women of loathsome appearance were publicly determined to be "loathly women". In this story, Dagnelle is actually anything but loathly; she is a beauty.
Gawain's Chivalry
The irony of Gawain's chivalry is that it actually wins him the most beautiful woman in the forest when it appeared that he was marrying a loathly woman. On his wedding night he decides to treat his new bride as though she were the most beautiful woman in the world - and in doing so, creates the reality that she actually is.
What Women Want
Going all the way back to the fifth century women have been telling men that what they really want is to be able to make decisions for themselves. Ragnelle tells Gawain that he can choose when he would like her to be beautiful; he takes the answer to the riddle to heart and tells her she can make the decision herself. Which of course, benefits him, because it lifts the curse, and his wife is able to return to her beautiful self for good.
Gawain's Sacrifice
Gawain agrees to marry the loathly woman - Ragnelle - and thereby sacrifices his chance of marrying a beautiful young damsel, so that he can save his uncle from beheading by Sir Gromer. The irony is that after he learns from the riddle, and treats his new bride as if she were beautiful anyway, he earns his beautiful bride, and no sacrifice is made.
Sir Gromer's Motivation
When we first meet him in the story, it is hard to like Sir Gromer very much; after all, he appears out of nowhere, fully armed, when Arthur is alone and without any means to defend himself. Moreover, instead of asking Arthur to return for a proper duel, he gives him a riddle to answer. The irony is that Sir Gromer doesn't want to kill Arthur at all; he just wants the spell that has rendered his beautiful sister loathly lifted. Because of this, far from being an aggressor, he and Arthur are actually on the same side.
