Frédéric becomes close to both Madame and Monsieur Arnoux and spends a great deal of time at their home. He earns Madame Arnoux’s trust, and she tells him about her background and about Arnoux’s changing careers. He is becoming vulgar, his business endeavors less honest. Frédéric advises her to leave Arnoux. When he is with Arnoux, he tries to convince him to leave Madame Arnoux. Frédéric likes Arnoux even though he is often irritating, but he is troubled to realize that Arnoux seems to be praising his wife more than usual.
Arnoux soon goes into heavy debt after an unwise business transaction, and his reputation suffers. Although others avoid the Arnouxes, Frédéric makes a point of seeing them as often as he always had. However, he begins to feel guilty about loving Arnoux’s wife. Arnoux, determined to avoid conflict, tells Madame Arnoux that Rosanette is not his mistress and that she is in fact Frédéric’s mistress. Furious, Frédéric tells Madame Arnoux it isn’t true. His position in the household is getting complex.
Deslauriers asks Frédéric for money to take over Hussonnet’s newspaper, and Frédéric agrees to give him the fifteen thousand francs he is expecting from his bank. However, Arnoux approaches him for a loan the next day, and Frédéric gives the money to him instead. He lies to Deslauriers about having not received the money. Arnoux is slower in paying it back than he promised, and when Deslauriers presses Frédéric, Frédéric says he lost the money gambling. Deslauriers declares their friendship dead.
Frédéric decides to write a history of the Renaissance. One day, Madame Arnoux comes to his room with her daughter, Marthe, and a maid. Madame Arnoux tells him that she and Arnoux owe money to Monsieur Dambreuse, and she asks Frédéric to talk to him to put off the repayment. Frédéric agrees, then they talk and walk in the garden; Frédéric gives her a rose.
Frédéric calls on Dambreuse, who agrees to wait to ask for repayment. He then offers Frédéric a job as general secretary in his coal company. Frédéric agrees to invest around forty thousand francs. He expects Madame Arnoux to be grateful for his help, but she sends only a brief reply.
On the day he is supposed to meet with Dambreuse about the job and investment, he instead chases after Madame Arnoux, who he has learned is at Arnoux’s factory in the country. It is less impressive than he’d been led to believe. She gives him a long tour, and he then hints to her about his feelings. She firmly rebuffs his advances. He returns to Paris, cursing her, and receives a note from Rosanette. He vows to go to her in revenge.
Frédéric visits Rosanette and takes her to the races. There, she begins to annoy him, and he is embarrassed to be seen with her in public. Still, he feels confident that she will become his lover. Cisy and Hussonnet talk with them at the racetrack; Cisy has become flamboyant and ostentatious. Many well-known men know Rosanette and greet her. When Madame Arnoux passes by, Rosanette raises her champagne glass and loudly greets her “protector’s wife.” Frédéric is horrified.
After the races, Frédéric and Rosanette go to dinner, where they are interrupted by Hussonnet and Cisy. Frédéric is outraged and embarrassed when Cisy takes Rosanette home. Hussonnet tells Frédéric about his newspaper. He has changed the name to Le Flambard. Frédéric ignores him, and Hussonnet leaves. Frédéric is stuck with the entire bill. He vows to become rich by playing the stock exchange as a way of getting back with everyone who has wronged him.
Pellerin visits Frédéric and asks to be paid for the portrait he painted of Rosanette—both Rosanette and Arnoux have refused to pay. Frédéric refuses as well, denying that he is her lover. Pellerin leaves, and Senecal arrives. He has just been fired from working for Arnoux and blames Frédéric.
Frédéric gets a considerable sum of money for selling one of his farms. He learns from Hussonnet that Rosanette got rid of Cisy a day after the horse races. When Frédéric runs into Cisy shortly after that, Cisy invites him to dinner. On the day of the dinner, Frédéric learns that the loan he made to Arnoux will likely not be paid back, since Arnoux had not applied for a mortgage at the right time.
Frédéric attends dinner at Cisy’s house, which is overly opulent. Frédéric dislikes Cisy even more because of the ostentatious display. A baron arrives and congratulates Cisy on his bet—at the races, he’d bet that he would go home with Rosanette. Cisy is embarrassed, since the morning after their tryst, Arnoux had arrived and Cisy had become an intrusion. The baron hints that he, too, has been intimate with Rosanette. Frédéric, humiliated at his failure to make her his mistress, tries to claim that she isn’t available to everybody, but this makes him look foolish.
Talk turns to Arnoux’s shady business dealings. Frédéric defends him. Cisy claims that the only good thing Arnoux has is Madame Arnoux, and then he makes a comment that suggests that Madame Arnoux is familiar to many men. Frédéric loses his temper and throws a plate at Cisy. Refusing to apologize, he leaves. Immediately, he goes to Regimbart and explains the situation. Regimbart suggests a duel. The next day, Cisy’s representatives arrive and tell Frédéric that Cisy needs only an apology. Frédéric refuses and requests a duel. Because Cisy was the injured party, he chooses the weapons: swords. Neither man wants to fight, but each also refuses to back down. Regimbart and Dussardier accompany Frédéric. At the duel, Cisy faints; when he wakes up and resumes the fight, Arnoux appears and halts it, declaring his gratitude to Frédéric. He believes Frédéric had been fighting for his honor.
Dussardier begins visiting Frédéric every evening. One night, he tells Frédéric that Senecal has been arrested for political conspiracy. The two men vow to help him. As Frédéric searches the papers for news of him, he finds an article in Hussonnet’s paper that makes fun of his duel with Cisy—although no names are mentioned. Then, in a shop window, he spots the portrait of Rosanette, to which Pellerin has added a sign saying it belongs to Frédéric. Frédéric fears he is becoming a laughingstock of society.
Determined to regain his respect, he attends an evening gathering at the Dambreuses. However, Madame Dambreuse hints mockingly at his role as Rosanette’s lover; then she hints that he is also Madame Arnoux’s lover. Dambreuse suggests he not get involved in business with Arnoux and tells him he needs to make up his mind about the job with the coal company. Sure he is being mocked, Frédéric leaves.
Dussardier visits and suggests that Frédéric contact Deslauriers. Once the friends are reunited, they ignore Dussardier. Frédéric tells Deslauriers about the possible job with Dambreuse.
Madame Moreau writes to Frédéric and suggests that he marry Roque’s daughter, Louise, since Roque has a large fortune. Frédéric goes to Nogent to see her and begins considering the possibility.
When Frédéric seeks out Madame Arnoux at Arnoux’s factory, the extent of what Madame Arnoux knows about his feelings for her becomes clear. Foolishly, Frédéric skips a business meeting with Dambreuse in the hopes of spending time alone with her; but his decision proves fruitless, as she seems determined only to give him a tour of the factory. For the first time, Frédéric has gathered enough will to try to tell her how he feels, but she rebuffs all of his advances. Madame Arnoux is generally very emotionless and calm, but here her stoicism proves to be a kind of virtue or determination, as she speaks in not-so-veiled language about what a married woman should and should not do. Frédéric, who has proven to be indefatigable when it comes to pursuing her, for once recognizes the dismissal for what it is. He does not handle rejection gracefully, and his desire to get revenge on her ultimately leads to disaster.
As Frédéric becomes wealthier, he proves himself to be a blank slate onto which others can write their desires. Without a clear idea of what he himself wants, he gives in to any suggestion that others put to him. When Deslauriers asks him for money for his newspaper, Frédéric agrees; when Arnoux asks for a loan to help with his debts, Frédéric agrees to that too. He cannot please everyone, let alone himself, and he ultimately alienates Deslauriers when he gives his money to Arnoux. On some level, he knows it is wrong for others to instantly claim whatever money comes his way, but he is too weak-willed to stand up for himself and assert his own wants and needs. He wants what others want, feels what others feel. But his generosity is not altruistic—instead, it is rooted in a lack of self-respect and failure to build his own identity. For now, Frédéric is whatever others want him to be.
Although Frédéric believes himself to be an accepted member of bourgeois society, his position is precarious and subject to the whims of others. Arnoux uses Frédéric as a pawn in his convoluted affairs, telling Madame Arnoux that Frédéric is Rosanette’s lover so as to take suspicion away from him. Both of the Arnouxes use him as a willing ear so that they can complain about each other, but neither heeds his advice to separate. His money seems up for grabs, and no one is much interested in what he wants for himself; both of the Arnouxes sing his praises and then forget him when he gives them what they need. Frédéric’s attempts to move further up the social ladder prove even more disastrous to his position. When he attempts to actually join the ranks of men who have slept with Rosanette, he is humiliated, as Rosanette prefers the wealthier Cisy. And Hussonnet takes revenge on Frédéric for not supporting the paper by publishing an embarrassing article about him. Frédéric sees himself as a shrewd, calculating person who can ingratiate himself in whatever company he desires, but his admirers turn on him in an instant.