After her conversation with Bresnahan, Carol looks at Kennicott more critically. She realizes that he does not dress well and has uncouth table manners. The unbearable summer heat makes everyone in town very touchy, especially Carol. One evening, Kennicott casually informs her that his friends are coming over to play poker. After everyone leaves, Carol tells her husband that his friends have rude manners. Carol and Kennicott have an argument and fail to make peace. The next day, Carol asks for a room of her own. Though Aunt Bessie tells Carol that married couples should not have separate bedrooms, Carol learns that Mr. and Mrs. Westlake have separate rooms. She decides to visit Mrs. Westlake and becomes her friend.
When the maid, Oscarina, leaves the Kennicotts, Carol cannot find a good maid to take her place and ends up doing most of the housework herself. Aunt Bessie and other women in town exhaust Carol with their opinions on housework. When Kennicott mentions that they should build a new house, she becomes excited and tries to make suggestions for a beautiful, original house. Kennicott, however, insists on building a house that looks exactly like every other house in Gopher Prairie. One day in July, he offers to take her to the neighboring town of Joralemon to visit friends. Carol feels disappointed with Joralemon because the town looks and feels exactly like Gopher Prairie.
Kennicott broods over Carol's highbrow attitude. He feels that she does not appreciate him and muses on the fact that some women could still find him attractive. However, he knows that Carol is the most beautiful girl he knows and he does not want to hurt her. One day, Maud Dyer comes into Kennicott's office complaining of a backache. Although she asks for an examination, he tells her that her symptoms are imaginary. They both agree that Maud needs to travel and be away from her husband, Dave, for a while. However, Maud tells Kennicott that her husband would never give her the money or permission to travel alone. She emphasizes how lonely she feels and asks Kennicott to visit her tonight to keep her company, adding that her husband will be away. Kennicott promises to visit her.
When Kennicott comes home, he plays with Hugh and feels repentant for being tempted by Maud Dyer. That night, the tailor, Nat Hicks, visits Kennicott and invites him to a party with women to relive their bachelor days. Kennicott refuses. Carol, however, disappoints him by acting coldly to him all night. When he asks her to keep him company that night, she refuses. Then, Kennicott tells Carol that he has to visit a patient and goes to see Maud Dyer. The next day, Carol finds her husband quiet and reflective, and she imagines that he is simply thinking about how the grass needs cutting.
Carol and Hugh love visiting the Bjornstams, and Carol views their house as a refuge where she can go to escape. Bjornstam and Bea treat their boys with equal love. They enjoy Carol's visits because, as a poor couple, few townspeople ever visit them. One day, Bjornstam tells Carol that he plans to leave Gopher Prairie because the townspeople will never respect him and Bea. He loves his family and great deal and buys Bea a phonograph.
Carol visits the Bjornstams again and finds Bea and Olaf sick with fever. Dr. Kennicott diagnoses their ailment as typhoid, which they have contracted from bad well water. Carol agrees to stay with them to nurse Bea and Olaf. She finds the work exhausting, but loves her friends too much to even think about complaining.
Both Bea's and Olaf's conditions worsen. Vida Sherwin, Maud Dryer, and the minister's wife call on the Bjornstams. Bjornstam does not welcome them inside, condemning them for not visiting Bea when she was well. The women leave, insulted. When Olaf and Bea die, the townspeople remark that Bjornstam probably mistreated them. Bjornstam leaves Gopher Prairie to move to Canada. Because many people in town dislike him, they cheer his departure.
The Kennicotts' deteriorating marriage provides the main focus of Chapters 24 and 25. The interior conflict of Carol and Will, who represents all of Gopher Prairie in many aspects, counterbalances the exterior conflict between Carol and Gopher Prairie throughout the novel. While Carol demands reform, Kennicott proves to be a willing slave to routine, "fixed in routine as an isolated old man." When Carol yearns for what she considers beautiful and noble, Kennicott scorns her highbrow attitude.
As literary critic Mark Schorer points out, the two protagonists prove to be familiar American types: the complacent husband who possesses common sense and solidity and the discontented wife who possesses romantic dreams. While Lewis presents Gopher Prairie as a microcosm for America as a whole, he also presents Carol and Kennicott as representative of the American husband and wife. In many ways, their struggle represents the eternal conflict between the opposite sexes, which Carol sums up in Chapter 24: "There are two races of people, only two, and they live side by side. His calls mine 'neurotic'; mine calls his 'stupid." We'll never understand each other. [We are] enemies, yoked."
Giving both Carol and Kennicott admirable traits along with character flaws—Carol's instability and dreaminess and Kennicott's dullness and materialism—Lewis does not take sides in the conflict between them. While most of the novel is told through Carol's point of view, Chapter 25 is the only chapter told entirely through Kennicott's point of view. Through the arguments between Carol and Kennicott, we see Carol through Kennicott's eyes as snobbish and temperamental and may even agree with his assessment of her.
Some critics have asserted that Main Street lacks a proper, consistent hero. While Carol appears silly to dream about reforming the whole town, she is one of the few characters who recognizes the town's ugliness, narrow-mindedness, and hypocrisy. On the other hand, Vida's plan for gradual reform appears more sensible and realistic, even though Vida proves too conventional and too willing to follow the crowd. While Lewis describes the heroic life of Kennicott as a country doctor, Will proves to be too crude and too content with a mundane small-town life to be a hero.
In Chapter 25, Lewis narrates the exchanges between Maud and Kennicott so subtly that we must read between the lines to understand what exactly happens. Throughout the novel, Lewis presents the atmosphere of small-town life as claustrophobic. The gossipy ladies in town form almost a network of spies, thinking that they can know everything about everyone in town. In fact, Gopher Prairie does not prove to be a haven for virtue as the romantic literary tradition of portraying small towns implies. Both Harry Haydock and Nat Hicks enjoy love affairs, and even Kennicott cannot resist the temptation of Maud Dryer. His affair with Maud further reflects the ever-widening separation between him and Carol.
Lewis uses Chapter 26 to attack the hypocrisy of small-town life. Although the townspeople attend church, claim to be charitable Christians, and affirm a belief in democracy, they still maintain a class-divided society and look down on the poor. Indeed, the fact that they do not care about the Bjornstams appears to stem wholly from the fact that the Bjornstams are poor. While Bea and Olaf literally die from their poverty, contracting typhoid from their polluted well water, the elite members of Gopher Prairie do not even recognize that poverty in the community exists. The socially conscious Carol, on the other hand, who does not attend church often, selflessly nurses the Bjornstams, displaying a humanity and Christian charity that most of the townspeople lack.