What is going on with Kanoko is an example of dialectical development.
Kanoko at the beginning of the story: I don't want reciprocity or intimacy from Hime-chan, as long as we have a very special platonic spiritual bond, I can't want more than that. That's the thesis.
Goeido: Your very special platonic spiritual bond means nothing if you don't want to fuck your Hime-chan. That's the antithesis.
Kanoko now (well, not really now, but she's definitely moving in that direction): I recognize the importance of the physical aspect of a relationship, but I also don't dismiss the primacy of emotional connection. That's the synthesis.
The only thing left for Kanoko is to realize that she already has a much stronger and deeper emotional connection with Sumika than she has with Hime in all the years since they have known each other.