How can Christopher look past his mother's behaviour, but not his father's? In what way does this reveal how Christopher's mind works?

Over the course of the novel, Christopher experiences a series of increasingly destabilizing events, such as learning of Mother’s affair and Father’s deceptions, revealing that Christopher’s narrow focus on order at the beginning of the novel actually keeps him—and the reader—blind to the complex tangle of relationships within his family. This disorder grows increasingly prominent as the story progresses. When Christopher leaves Swindon to find his mother in London, he becomes literally paralyzed at times by the disorder of the massive urban landscape he passes through, which symbolizes the disorder he faces in his family. The novel concludes with the various characters resolving some of their issues, but with their lives remaining essentially as untidy as ever.

This impulse to protect Christopher and his desire to punish Christopher’s mother for the way she left leads him to lie to Christopher about mother’s leaving. As Christopher discovers more and more of the truth about his mother, Christopher’s father can see his relationship with Christopher deteriorating. Christopher’s father must work to regain Christopher’s trust, and the novel’s final chapters focus on his efforts to reestablish a relationship with Christopher.