That evening, Jane is well enough to join the group. Bingley dotes on her and talks to no one else. Caroline, watching Darcy read, pretends to be absorbed in reading a book. But she's soon bored and suggests to Elizabeth that they walk around the room together. This gets Darcy's attention.
Conversation, books, walks: these are the few tools of seduction in Austen's world. Caroline has to work to get Darcy's attention. But by doing what comes natural to her, Elizabeth gets it anyway.
Caroline invites Darcy to join them, but he says he doesn't want to interfere: they must either be sharing secrets or showing off—in which case he's happy to watch.
Sexual attraction in the novel are expressed only in little comments like these. But it's definitely there.
Elizabeth advises Caroline that the best response is to laugh at what is ridiculous, which leads to a discussion of the aspects of Darcy's character that might be ridiculed. Darcy claims that his main fault is that "my good opinion once lost is lost forever." When Elizabeth retorts that it is difficult to laugh at a "propensity to hate every body," Darcy says that if his defect is holding grudges, Elizabeth's is misunderstanding people.
Darcy incorrectly identifies his own flaw, which is the immense pride he takes in himself and his social standing. But he correctly diagnoses Elizabeth's: she believes so fully in her own ability to see to the heart of things that she becomes subject to her prejudices and blinds herself to the truth.