I see many people agreeing with the the way the seme handled things, but it is a matter of subtlety . Of course he was gonna be taken aback, but not like that. It was not a treason or cheating, he didn't have any other student, also if the uke liked the seme, of course he would delay telling the truth until he had a better opportunity (yeah, of course in rl he would have need to tell him way sooner). Point being, the uke apologized, said he's in love too, said he didn't do it with somebody else... Plus, hiring a teacher to learn having sex sounds VERY similar to hiring a prostitute, teacher could be mad about that too.
So... Yes, exaggerating for the sake of drama. I love drama, just prefer it less forced.
Honestly this drama seems so misplaced. I can imagine Hojun being upset but it seems like the drama was blown out of proportion by the author to make it part of the storyline. ( ̄へ ̄)