What is the significance of the title, The Break Down?

In context, the title symbolizes the essence of the narrative itself, as a breakdown can mean the many things that happen in the narrative. A car can breakdown and Cass thinks that this may have happened to the woman she sees on the side of the road. A person can have a mental breakdown and that is what Rachel and Matthew try to make Cass think that she is having. There is also the breakdown of trust. This is what happens when Cass first believes that she is losing her memory and she stops trusting herself. There is also a breakdown of trust when she realizes that someone is trying to make her think that she is losing her memory. She first stops trusting John and later Matthew and Rachel. In addition, there is the breakdown of relationships and the relationship that Cass realizes that the relationship she has with Matthew and Rachel has broken down and is rotten.