i think he might be feeling something complicated about what it means to be loved by heejae. he knows the prof loves him, but he's frustrated that the prof seems to have forgotten (or never even realized) that he was the one who scarred garam's face. and then hearing heejae talk about how you shouldn't forgive people who've hurt you in the past just because they're being nice now...garam definitely feels the prof's inconsistency and it's fueling some doubt in him.
that said, i do think he's very much in love. what could happen is he buries these uncertain feelings rather than talking them out with heejae and they become a wound in him that wont get healed (hence the last frame of ch. 201 w/ the closeup up his scar).

is garam losing feelings