The way he’s been nicer progressively for like 30 chapters lmao. Her Characters are human , when someone’s triggered they revert back to their old ways that makes him realistic . It’s obvious he’s doing this as a defense mechanism not only by his past being brought up but also trying not to get hurt by Dan (unintentionally)
I love how you say "nicer" because in those 30 chapters he was never really nice. Just not as horrendous an asshole as when he first started. I don't need him to change immediately but a hint of actual growth or trying to regulate his own emotions instead of lashing out like a five year old every time a hint of crisis appears would be appreciated.

Where is it lmao?
I'm sorry but Mingwa you suck. So bad. What is this.
This could have been the point where we are shown that Jaekyung is at least t r y i n g to change.... Instead he was nice for two days and goes right back to absolute asshole.