
the thing is their relationship is founded on a lie or ''joke'' that snowballed out of control and that's why Hojun is pissed because he was pretty much played for a fool. Even if Ahns' feelings became sincere afterwards he kept up the charade for so long and that's a pretty big pill to swallow. I like both of the characters but Hojuns' reaction is pretty understandable.

I dont get the whole relationship startd as a joke thng... a relationship startn as a joke would be going out with someone on a dare... this is not that... he found him over a ‘joke’ but he took his job seriously and researched alot n helped him in alot of ways... so how was it a joke... he did exactly what he said he would even if he was serious about starting... its not the same at all to me

you're looking at it from your perspective tho from an omniscient 3rd party point of view you saw the hard work Ahn put in and you can read his thoughts and see he didn't have bad intentions but Hojun can't, all he has is what he experienced and what ahn just told him and from his perspective and what he's heard, it all started with a drunken darejoke and that while he was agonizing about Ahn sleeping with other students ahn knew the whole thing was a farce and never told him that he didn"t have any other pupils. Anyone would feel ridiculed in a situation like that . MMmmmmm i guess its kind of a mix of feeling dumb and also realizing you've been lied to. Hojun came into the experience with an open heart and expected reciprocity(.ie no lies) he was also having a vulnerable moment while confessing his feelings so i feel like his emotions were amplified.
Is it really that big a deal or am i just stupid... its not like its a actual profession... whether he was serious teacher in beggening or not shouldnt matter... shit i dont thnk any of my college teachers were serious