The lake house is a central symbol in the book, representing the marriage alluded to in the novel’s title. Initially, the lake house represented fresh hope in Sarah and Adam’s marriage, as it was a second home where they could go to get away from the pressure of the city, including Sarah’s job. However, Adam mostly spends time there alone or having an affair with Kelly/Jenna: The lake house has thus evolved to being symbolic of their crumbling marriage. The lake house then becomes a literal scene of the crime, embodying the deceit and infidelity that has plagued Adam and Sarah’s union.

After the murder, the lake house functions as a semi-prison for Adam, who is kept there under house arrest. As Adam grows more suspicious of Sarah, he becomes more determined to break out of the lake house. His desperation to flee the house mirrors his desperation to flee her marital control, suggesting that the marriage—just like the lake house—has become a form of entrapment for him.

The lake house gains prominence once again in the book’s final chapter, when it is revealed that Sarah, Bob, and their daughter, Summer, now live there full-time. The lake house has once again become a symbol of marital hope and bliss.