Marriage
This novel is an elaborate satire about marriage, about the various pitfalls of relationship, and about toxic masculinity and toxic femininity. Because of its absurd tone at times, the serious drama of this couple (miscarriage, alcoholism, drug addiction and recovery) devolves in a near farce. The same chronic difficulties in Will's life are just exacerbated by Kellogg's misguided therapy, while Eleanor is given hospitality and generosity—her therapy is basically just pleasure.
Therapy
Therapy itself comes under the microscope in this story. From the satire, we see a picture of Kellogg's sanatorium as a place where women are coddled, and men are abused. Will has a friend who is also in therapy at the institution, and Will watches as Kellogg's clumsy theories lead to that friend being literally electrocuted right in front of Will. Meanwhile, Will's treatment is more like humiliation. They try to strip Will of his dignity by taking power from him in his marriage, and in his real life.
Authority and ethos
The plot seems specifically designed to criticize "ethos." Ethos is the hypothetical currency of authority. Because Eleanor has read about Kellogg, she feels a delight when meeting him; it makes her feel like she's talking to someone important. In this novel, that is a serious problem, because that ethos allows Eleanor and Kellogg to form a kind of automatic trust using credibility that Eleanor would never have afforded Will. Will's authority to speak for himself is completely removed from him.
