One of the students had a crush on Mr. Schuester
Oh, Rachel Berry, a character who starts off consistently being so much. In the early episode "Ballads" (Season 1, Episode 10), the club is divided into pairs to perform renditions of ballads; when Rachel is left without a partner, Mr. Schue steps in to sing with her. Inevitably, Rachel becomes infatuated with her duet partner, giving him unwanted attention. Admittedly, yes, Mr. Schue is a stereotypical "hot" teacher, being young and hip and relatable and a killer performer -- and what would Glee have been if not the perfect opportunity for a problematic teacher/student affair? But it’s also a destination they did not have to arrive at. Yet, they did -- along with a side story about a former student named Suzy Pepper who was so obsessed with Mr. Schue that she attempted suicide because of her unrequited feelings.
Instead of letting Rachel down easy to avoid that from happening again, serenading her seems like the next best option! He mashes up "Don’t Stand So Close to Me" by The Police with "Young Girl" by Gary Puckett and the Union Gap, which might seem like a clear message, but to a lovelorn Rachel, she’s very into it. Actually, somehow, she misconstrues the lyrics into meaning her teacher is so attracted to her, he can’t stand to be near her. It was an admirable decision to never write a romance between them into the plot for the sake of dram', but it’s still an uncomfortable moment that’s difficult to watch as it unfolds.