What is the main conflict in A Reliable Wife by Robert Goolrick?

This novel of sexual intrigue, betrayal, and redemption concerns the experiences of two principal characters, Ralph Truitt and Catherine Land, who at first appear to be very different but are ultimately quite similar. As the narrative gradually peels back the many layers of secrets and sufferings in the lives of each of these deeply troubled characters, it also explores themes related to the power of sexual desire, the unpredictable nature of humanity, and the dangers of isolation.