"Oh! she is the most beautiful creature I ever beheld! But there is one of her sisters sitting down just behind you, who is very pretty, and I dare say very agreeable. Do let me ask my partner to introduce you." (Chapter 3)

"It will be her turn soon to be teazed," said Miss Lucas. "I am going to open the instrument, Eliza, and you know what follows." (Chapter 6)

"My dear Miss Eliza, why are not you dancing? -- Mr. Darcy, you must allow me to present this young lady to you as a very desirable partner. You cannot refuse to dance, I am sure, when so much beauty is before you." And, taking her hand, he would have given it to Mr. Darcy, who, though extremely surprised, was not unwilling to receive it, when she instantly drew back, and said with some discomposure to Sir William -- (Chapter 6)

Lizzy is sensitive on this point I now see--Darcy thinking she is out to fix him. It started with Bingley as you say in Chapter 3, then Charlotte with the pianoforte and later in Chapter 6 it will be Sir William setting her up before Darcy as a desirable partner. It seems the only thing worse than being only tolerable is being the offered prize. I never really took this pattern to heart before and the first two incidents make Lizzy’s refusal to give in and dance so much more logical than just Lizzy returning the favor of not dancing with him—a small act of revenge. I do not mean to imply that Lizzy should want to dance with him or anything of that nature—he has not made himself agreeable to her the least bit but I have felt the refusal was almost a slight against Sir William who is being a good host and trying to bring the two together for some amusement. Little does he know of course! Bingley and Sir William are probably puzzled by Lizzy and Darcy’s behavior while Charlotte is likely the only one the three who has a clue to what is going on. ;D LoL!