yess, in general the professor is super jealous of anyone, even sponsors who like Garam's performance and try to approach him. He's so possessive over Garam.
Krueger actually develops feelings for Garam and they play a duet, which Garam hides from the professor. The professor finds out and goes to see them perform and gets insanely jealous because it looked like Garam was enjoying himself too much. He keeps being jealous of Krueger even when they hang out as friends.
They also also meet Compton, the first of the professor's disciples, and Garam manages to win him over (in a convoluted way but anyways it's worth it) and the professor doesn't like him hugging Compton at the end of performances or when they say goodbye at the airport.
Miss Claren also kind of catches on their relationship (I like that she doesn't get upset over it, she only cares about the professor's performance) but the professor tries to deny it so she asks him whether it'd be fine to sleep with Garam for fun if they're not involved that way and he immediately snaps at her saying absolutely not.
Anyways once the professor accepts his desire and then his feelings for Garam he unleashes his full jealousy and possessiveness so you've got that to look forward to!

Like Garam should have at least 47 people fighting to the death for his hand, hes literally too fucking CUTE and I need someone to keep the professor on their toes!!
I will SCREAM if his ex from Gaeum comes to his debut recital, they needta knock boots at least once, just for old times sake