Not to say that the way that she was acting is justified, but I understand the emotion behind Narumi's actions. I've been in the same kind of situation myself, and BOY! Pride and jealously can make us into ugly people.
Excluding the degenerate comments:
This is such a beautifully tragic story so far.
I loved Kids on the Slope, and everything this Mangaka creates seems to have the same effect on me!
Can't wait to continue.