|Darcy with a headache.|
The party is the assembly ball at Meryton where Darcy makes such a bad impression. The characters present perceive Darcy as proud/unapproachable. I wrote Darcy as uneasy, uncomfortable, with the beginnings of a headache. It is very easy to mistake the latter emotions for the former attitude.
Channeling Darcy's emotions of discomfiture was remarkably easy. I grew up with a dad who would quietly, not at all rudely, slip away from parties, even in his own home, after an hour or so. A few hours of chatter was enough to fill his people quotient for the weekend, even the week.
In addition, my idea of hell is an endless cocktail party. Fire and brimstone sounds downright relaxing in comparison. I'll even take snow and ice. But people standing around with napkins and cheese cubes on sticks, discussing job promotions, car loans, vague politically-correct politics is the kind of thing that makes me want to run for cover, any cover, as quickly as possible.
Consequently, I can easily understand Darcy's curt desire to stop talking and dancing and talking, etc. etc. etc.--despite Bingley's insistence--rush home and settle down with a good book.