Not so much a love triangle as a love line segment.
I lol'd.
This little story pretty much made me realize I would be a terrible teacher in Japan. If I were the advisor, I would destroy that band. One of the substitutes is super skilled but pushed out because they don't like her? One of the other substitutes sucks and rather than practicing MORE they are making her run errands? What if your clarinet player gets a cold and you NEED her to not suck? I would be hated because I would violate every bit of Japanese power dynamics. Like in that anime we all refuse to mention.
Also, I'm a flute player and have had that "too nervous to play" thing happen to me. Obviously I'm a guy so the circumstances are different but hell does it suck. It was the worst.