Although I usually enjoy Claire Messud's books this one left me feeling like SHE, Claire, missed the point. The woman upstairs feels betrayed & used, disrespected, at the end of the book.
To me it seemed she had only gotten payback for having been disrespectful of Sirena by trespassing in her studio space & using Sirena's vision to get off on as though it were her own. The woman upstairs seemed to me an angry narcissistic person who decided to take on the victim role & be resentful about it.