What is the most important room in the home Katrin and Eric shared in the novel, The Life-Writer?

The library is one of the most important rooms in the house that Katrin and Eric share. It is in the library that Eric keeps the books that are such a core part of his life. In an effort to begin moving on, Katrin decides the library must be remodeled. She gives away the books and dismantles the shelves. The library becomes a point of change as Katrin seeks to move on in her life.