How does Gregor respond to his sister's violin playing, and what might this reaction imply about him?

In Part
3, Gregor hears his sister, Grete, playing the violin for the three gentlemen boarders, and he
"dare(s) to come forward a little" to hear it. He is described as captivated by the
music, much more so than the three boarders are, and he wishes that she "might come into
his room with her violin" and play for him rather than them. His reaction to the music is a
reminder of his affection for his sister and is in stark contrast to her reaction upon seeing
him present, which is a reaction of disgust and contempt. This bond with his sister, represented
by his response to the music, is the last bond to break, and this moment signals his complete
and irreparable separation from his family and from his former human self.

Earlier in the story, in Part 2, Kafka writes that it was always Gregor's "secret plan to
send (his sister) to the conservatory," because, even though she was more fond of music
than him, he nonetheless appreciated what a "gifted and expressive violinist" she was.
After...