When Emma returns to Yonville, Leon begins inventing pretexts to visit her there. He neglects both his work and his friends in Rouen. Emma continues to sink deeper into debt to Lheureux and convinces Charles to let her take a weekly piano lesson in Rouen, secretly planning to see Leon on a regular basis.
Every Thursday, Emma travels to Rouen, where she sneaks through back alleys in poor neighborhoods to see her lover. She feels emotionally alive during her time with Leon and is anxious and withdrawn at home, even though she continues to act the part of the dutiful wife. Her relationship with Leon grows more intense with each encounter, and the two begin to view one another as characters in a romantic novel. She develops a familiar routine of going to visit him and returning in the carriage to Yonville. On the road between Rouen and Yonville, she periodically encounters a deformed, blind beggar who terrifies her with his lurid, horrible song. At home, Charles nearly discovers the affair when he meets Emma’s alleged piano teacher and finds that the teacher does not know Emma’s name. But Emma shows him forged receipts from the lessons, and Charles is easily convinced that nothing untoward has occurred.
As a means of paying her mounting debts, Lheureux convinces Emma, who has power of attorney over Charles’s property, to sell him some of Charles’s father’s estate at a loss. He also talks her into borrowing more and more money. When Charles’s mother arrives to look over the accounts, Emma has Lheureux forge a bill for a smaller amount of money than she has actually borrowed. Nonetheless, the elder Madame Bovary burns Emma’s power of attorney. Charles, however, soon agrees to sign a new one.
Emma is obsessed with her time with Leon, and with experiencing every kind of romantic pleasure. When she stays overnight with Leon in Rouen without telling Charles, she makes her husband feel foolish for worrying about her. From that moment on, she goes to see Leon whenever she feels like it, and he starts to become annoyed by her demands on his time.
One day when Emma is scheduled to be in Rouen, Homais pays Leon a visit and monopolizes his time. Emma is left waiting in the hotel room and becomes hysterically angry, accusing Leon of preferring Homais’s company to hers. She returns home in a rage, beginning to convince herself that Leon is not the man she thought he was. Emma starts to act domineeringly toward Leon, who reacts with resentment.
A debt collector surprises Emma with a visit, and the sheriff serves a legal notice against her. She borrows more money from Lheureux and begins a desperate campaign to raise money to pay her debts, even pawning many objects from Charles’s house in Yonville. All the while, she continues to spend decadently during her time with Leon, forcing him to entertain her opulently and providing him the money to do so. He becomes sick of her petulant extravagance, and she becomes disgusted with his reticence. Each of them is bored with their affair. She begins cavorting with unsavory company, even accompanying some vulgar clerks to a disreputable restaurant after a masquerade ball.