Despite its exploration of profound themes and a complex storyline, The Pilot's Wife primarily offers a portrayal of a marriage seen through the lens of loss and evolving situations. Kathryn often ponders, "How do you ever know that you know a person?" as she contemplates how we initially perceive someone by forming a mental image, gradually filling in the "missing brush strokes, waiting for form and color to materialize." While the novel delves deeply into the nature of grief, it also vividly illustrates the structure and essence of Kathryn's marriage. Frequent allusions to vision and related metaphors underscore the significance of introspection and self-awareness.

As Kathryn experiences the typical phases of grief, she fixates on details such as Jack's final words, questions whether she'll ever sleep again, imagines hearing her husband on the stairs, and is amazed by "the way the body kept moving forward, past the shock and the grief, past the retching and the hollowness inside, and kept wanting sustenance, kept wanting to be fed." She is taken aback to find that the initial shock starts to diminish and that gradually Jack's death "didn't rock her as violently as it had the day before." Despite this, Kathryn must constantly deal with memories that linger "like mines in a field, waiting to detonate." While on a flight to London, she becomes overwhelmed with thoughts of Jack's death, replaying it vividly in her mind.

Kathryn's sorrow is sometimes intensified and at other times alleviated by her concerns for her teenage daughter, Mattie. Mattie swings between feelings of guilt, bouts of depression, and holding her mother responsible for her father's passing, primarily because Kathryn is the closest outlet for her anger. Kathryn wishes her daughter could slip into a coma and "then awaken to a consciousness dulled by time, so that she would not be hit again and again with the pain that was always absurdly and cuttingly fresh." As a caring parent, Kathryn acknowledges that children are always in the process of leaving, "incrementally at first, and then with head-spinning rapidity." Yet, Kathryn's awareness of how little she knew about Jack reflects her grief over gradually losing her daughter. When Mattie opens up to her mother about having had sex, Kathryn is mostly troubled because she hadn't anticipated it, and because her daughter's experimentation was driven by curiosity rather than affection. It saddens Kathryn to realize how little she knows about those she loves most: "I didn't know about my daughter's sexual life, and I didn't know about my husband's sexual life."

Kathryn's grieving process is uniquely challenging due to her husband's infidelity, compelling her to reevaluate her entire life with Jack and explore her own sense of self. She had previously seen her relationship with Jack as evolving from "being in love to just loving," a view that is increasingly questioned with each new revelation. Every memory of Jack is now shaded with new insights—whether it's their infrequent arguments, his unexplainable anger on his mother's birthday, times when he seemed aloof or mentioned divorce, or the dynamics of a conflict that escalated as Kathryn wavered between guilt and bitterness.

Kathryn needs to reassess her concept of a traditional marriage, which she once believed involved a couple living "in a state of gentle decline, of being infinitesimally, but not agonizingly, less than they were the day before . . . which means, on the whole ... a good marriage." As her view of her marriage and her perception of Jack evolve, Kathryn comes to understand that she knew him well enough to comprehend some of his motivations. She realizes he would have been drawn to Muire's intensity and passion, as well as the excitement and idealism associated with risky political engagement.

With her newfound clarity and self-awareness, Kathryn is able to move toward forgiveness. This journey fosters increased self-reliance and allows her to be more open to future relationships. Nevertheless, she is still troubled by the "impossibility of ever knowing another person . . . the fragility of the constructs people make."