I really wanted to like this book and I thought the topic was interesting and provocative, but the main character was SO unlikeable. Her obsessions were cringy and grossly unhealthy and there was no acknowledgement that this kind of "attraction" was mentally unhinged. Not to mention that there seemed to be no reason for her attraction to either of her obsessive loves.
Plus, there were so many narrative tendrils that were started and never finished, primarily the basis for her title. We don't find out about "all fours" until the very end of the book and she never links it to any part of the story. Her desk had one short leg for twenty years and I thought she might link those two images somehow, but she didn't. Most importantly, the ending was awful. I kept hoping she would have some kind of redemptive arc where she developed an awareness about her unhealthy and self-pitying obsessions, but that never happened.
The good side of the book is the writing itself, which is excellent. The room itself was a fantastic creation and the idea of having a room where one can be totally oneself was a lovely part of the book. Many of her other ideas were also clever, but as a whole, the book did not hold together. The main character remained awful from beginning to end.