... that they are one and the same person? Fight Club type of thing? Just an idea.
Everybody lies
That very much occurred to me, particularly at the end. To me, this film seems inspired by Bergman's "Persona" more than "Fight Club."
shareI think Catherine is alone when she's depressed. She lost her dad at first. Then she lost Ginny because she wasn't there for her when she needed Catherine. After Catherine left the house(end of the movie), Ginny killed herself.
When Catherine comes back after losing her, she puts herself in her position. She goes through the same stories, events, situations Ginny had to go through when she was there with James.