I do think the turn of public opinion against Darcy in Chapter 3 is warranted and to go further, their good opinion was his to keep or loose as he chose. I agree with Mandy N as to Darcy’s duty to Bingley in this situation. I feel Darcy came to the assembly of his own free will and should have put himself out a little, a very little even to be agreeable to Bingley’s new neighbors. I think he lets his friend down in a way—that is how I see it, not that Bingley does of course. I can only think of how disappointed in a friend I would be if they treated others of my acquaintance with the distain that Darcy feels free to distribute. I think the townspeople were impressed with Darcy’s wealth and consequence but what I think they expected most of him and not unreasonably, was that he would act like a gentleman. Bingley’s comments seem to indicate that dancing is not an unreasonable expectation for a young man at a ball to live up to:

"Come, Darcy," said he, "I must have you dance. I hate to see you standing about by yourself in this stupid manner. You had much better dance." (Chapter 3)

I do not think it is failing to dance that is Darcy’s downfall however but his refusal to socialize at all and his obvious distain for the local people. Darcy not only disparages Lizzy’s consequence and appearance in particular but that of all other local ladies—“You are dancing with the only handsome girl in the room…" and also the assembly itself saying “At such an assembly as this it would be insupportable” to dance. Lizzy tells her friends the story of Darcy feeling above his company with great spirit, believing it to be ridiculous. I think she is right; Darcy’s comments seem so prideful as to be in the realm of the ridiculous and seems to be almost a rationalization for his failure to behave in way that can be reasonably expected from him at a ball—that is to socialize. A little effort on Darcy’s part could have prevented the change of public opinion but I do not think he cared either way what the Meryton townspeople thought of him. I think it is reasonable and fairly natural for people to change their good opinion to a lesser one when a person makes a point of saying he thinks so little of them. ;D