The little green monster represents the female protagonist herself. This symbol is established in the beginning of the story when she spends the entire day looking out the window, and finds herself unable to do anything else. The same goes for the monster he can see but he can't do much else. The reader can also assume the monster represents the protagonist in that many lines suggest the monster coming from "inside" from "deep deep down." The symbol is used by Murakami to portray his view on females. Perhaps the story is an attempt to show understanding for the woman's plight, or maybe the story is a direct criticism on woman's failure to "do," but either way it shows that Murakami feels that woman does little else but watch.
This idea is supported by the last part of the quote which is also the last line of the story. "Soon the eyes dissolved into emptiness, and the room filled with the darkness of night."
This line is paradoxical because it claims the room was filled with darkness of night. Darkness of night is no tangible thing. In fact, darkness is often used to represent emptiness, or an absence of light. By saying the room was filled with an absence of light, Murakami creates a paradox. The idea of filling something with emptiness can be applied to this woman. She is chock full of nothing. The lady does nothing all day, but by default she has to be filled with something, so that something is nothing... does that make sense?
Another thing the author uses is point of view. Once again a male Murakami chooses to write as a woman. The peculiarity of this choice shows an ulterior motive. So, I choose to believe that he does so to expose something of his view on women. Plus in the beginning of the book, he writes how she finds herself with nothing to do after her husband has left. Besides this in the quote above when she starts speaking sentences that begin with the word, "you," a deeper meaning is revealed. The point of view is a bit strange here because though she is in first person, she is also talking, or rather, thinking to a green monster. The way she talks to the monster by thinking thoughts in her own head automatically makes the reader wonder if these lines apply to her. The lines that begin with you in the above quote, I feel, start by apparently being directed towards the monster, but something changes that makes me think she is talking about herself. It's sad. Maybe it's the syntax of placing "finished" after "over", and "done" after "finished"; "over, finished, done." It sounds like a resignation, a gradual realization. Like "hey monster you're over... we're finished... I'm done, aren't I."