This chapter is structured as a “hypothesis.” The first part of the hypothesis is that Kathy has a secret lover. During her seventh day at the cottage with John, Kathy may have been thinking about this lover: a simple, honest man, totally unlike her deceptive, secretive husband. This is only a possibility, the narrator acknowledges.
In this chapter, O’Brien makes explicit what he’s already been implying—we can’t take anything we read at face value. Just as the contents of this chapter are only one possible version of the truth, the testimony we find in the surrounding chapters is equally warped by first-person perspective. Rather than ever get to a point of revealing “this is what happened,” O’Brien circles around all of the things that might have happened. The story is both obsessed with figuring out “the truth” happened and also obsessed with the fact that you never can.
Perhaps Kathy couldn’t bear to tell John about her secret lover. She may have staged her own disappearance—this is unlikely, the narrator admits, but not impossible. She could have woken up early, arranged for her lover to pick her up, and driven away.
Even though this chapter is framed as a possibility, it begins to tell us more about John and Kathy’s relationship—the mere possibility that Kathy had a lover is itself an important fact: clearly there was tension between John and Kathy, and clearly some of the tension stemmed from John’s propensity for lying and deception—in short for being a politician.