I feel sorry for him, but I also find him a bit annoying and am glad for the current ship - BUT, in so many other stories, with just a small change of the reader's perspective, he'd totally be the puppydog MC and we'd want the teacher to go away! Hehe.
Yes, he was a little bit of a bad sport when it came to the landlord, he was possessive and "staking claims" even though they aren't in a relationship. This latest chapter, however, shows that he just fell in love, life was boring to him, then he looked up, saw this senpai and his eyes widened. It was cute. If you think about it, he's pretty civil to the teacher normally, it's more of just when he gets jealous because he sees his crush being hit on that he gets a little douchey. Seems he's a jealous, possessive guy. Some people might find that unappealing, though i think it's a matter of taste. To a certain point, of course. But he's not harming the landlord with his jealousy. I'm sure we'll get more likeability from him soon.
I'm dying, he's really cute and i feel sorry for him. :‘^( Glad things are going well between landlord and teacher though. Hopefully Hui Soo is just acting weird because she has feels.