Isabel sits in the drawing room listening to Pansy and Lord Warburton converse; she is pleased by the way Warburton treats her stepdaughter, noting that he speaks to her as an equal. She wonders briefly what Pansy will think about her father and Madame Merle's dismissal of Rosier, but she decides that Pansy is so passive that she will probably not be terribly hurt by it. After Pansy and Warburton leave, Osmond enters and asks Isabel about Warburton's visit and his intentions toward Pansy.
Their conversation is strained; though Isabel is honestly trying to be a dutiful wife, he is angry that she failed to tell him about Warburton's interest in his daughter. Isabel insists that because their relationship is distant, she has not had an opportunity to tell him. He acknowledges that he wishes to see Pansy married to this powerful English lord and tells Isabel that he will expect her help in bringing the marriage about. He says that because she rejected Warburton when he loved her, she will now be able to influence his feelings.
Left alone, Isabel thinks about her relationship with Osmond. She wants to be a good wife and had planned to help him effect the match between Pansy and Warburton—but as soon as he pressed her to do so, she felt disgusted by the entire proposition. She is miserable in her marriage, though she was full of confidence at the outset. After a year with him, Isabel realized that Osmond despised her, and she understood that because she had tried during their courtship to seem exactly the way he wanted her to be, he believed that she would become that ideal person in their marriage. She realizes further that it was her imagination that enabled her to love Osmond, because it constructed such a powerful, romantic illusion of him that she was able to believe. She realizes that Osmond's life is defined by his arrogant notion of himself as a superior gentleman and his deep desire to have the world acknowledge him as such; where she thought that their life together would be one of intellect and liberty, he intended it to be one of social conventions and poses.
She realizes that her husband is ashamed of the fact that she has her own mind and that she disagrees with many of his ideas—for instance, his assertion that all women are dishonest and unfaithful to their husbands. Osmond wanted to own her like an object in his collection, and he is irritated and threatened by the fact that his acquisition has her own ideas and her own way of looking at life. Isabel suffers greatly when she thinks about her marriage. She is also sad to think about Ralph, who is growing weaker and sicker, and whose goodness Isabel only now appreciates fully. At four o'clock in the morning, Isabel rises and readies herself for bed; she is suddenly struck by a memory of that she saw earlier that day: Osmond and Merle, gazing silently into one another's eyes.
Isabel escorts Pansy to a ball, where she acts as her stepdaughter's chaperone. As she holds Pansy's flowers and watches her dance, Rosier approaches her, looking sorrowful, and asks to take one of Pansy's flowers. Isabel allows him to take a flower, but as Pansy leaves the dance floor to approach them, Isabel asks Rosier to leave; Osmond has forbidden Pansy to dance with him. Warburton arrives and stays to talk to Isabel when Pansy rejoins the dance. Isabel is surprised that Warburton has not asked Pansy to dance the cotillion, a very long and intimate dance but instead has asked for the quadrille, a dance that involves a large group. Warburton says that he hopes to talk to Isabel during the cotillion.
Isabel realizes that Warburton is still in love with her and is pursuing Pansy only to be closer to her. When Warburton sees Rosier looking dejected, Isabel tells him that the man is his rival for Pansy's affections and that he is in love with her. Looking guilty, Warburton acknowledges that he is not in love with Pansy and tells Isabel that he can no longer pretend; he goes to write a note to Osmond. Isabel finds Rosier and promises that she will try to help him. As the ball ends, she finds Warburton and tells him to send the note to Osmond.