Whenever Léon visits Yonville, he stops by the pharmacy to see Monsieur Homais, and they idly plan to have lunch in Rouen together sometime. One Thursday, when Léon and Emma are supposed to meet, Monsieur Homais suddenly shows up at Léon’s work. Léon sees no way out of the lunch invitation, so he goes along. He repeatedly tries to get away, claiming that he has to go back to work, but Monsieur Homais refuses to hear of it.
Monsieur Homais's visit goes on for hours. At one point, Léon manages to get away briefly to confer with Emma in secret. She orders him to get rid of the old bore and spend the rest of the day with her. He tries, but Monsieur Homais proves difficult to shake off. Emma waits most of the day, then grows furious and goes home.
After this incident, Emma and Léon never feel quite as close as before. Rather than accept this and go on with life, Emma does everything she can imagine to regain the initial excitement of their affair. In bed, she loses all her inhibitions. Léon is a bit scandalized.
One day, Emme learns that Monsieur Lheureux has sold some of her debt to a debt collector in Rouen. The debt collector’s swift legal demand for repayment comes as a shock to Emma, who rushes to Monsieur Lheureux’s store to complain. He says that he can do nothing to help her because he is short on money himself. Then he manipulates her into borrowing yet more money and also buying a length of expensive lace.
Now quite worried about money matters, Emma begins selling her old possessions and pressing her husband’s patients to pay their medical bills. She pays off a few debts here and there, but she always seems to end up spending more. Charles knows little about her financial missteps. When he finds out about a few of them, he attributes her errors to her frailty from her illness.
Meanwhile, Léon feels that his relationship with Emma is getting out of control. Rumors about him have reached his mother and his boss. His boss pressures him to break off the affair. Léon promises to do so, but he is too weak to follow through. He continues seeing Emma, although their affair is slowly becoming “as banal as marriage.”
One Thursday, Emma stays in Rouen and attends a masked ball with Léon. She dresses as a boy and stays out all night. Although initially excited by the novelty of this, Emma soon reconsiders her opinions. Everyone in her group is wearing a mask, but many speak in voices that sound frighteningly low-class. Emma begins to worry that her life is moving in the wrong direction.
When Emma arrives home, she finds a court document nailed to her gate, stating that she owes eight thousand francs—a sum far more enormous than any she ever borrowed. Monsieur Lheureux has sold the entire debt to a debt collector, who is demanding full repayment. Emma rushes to Monsieur Lheureux’s shop, and he says that he cannot help needing his money back. He tells her that a woman like her, who has “plenty of friends,” should have many ways to pay debts. She begins to weep, and he kicks her out, slamming his door in her face.