Libulan

I think Qin did say your looks got on my nerves in the drama and I did say he noticed Duang for his kind nature as well
Maybe as you said Duang's loud and boisterous nature may also have intrigued Qin cause they were total opposite of each other
It may have been a little bit of all these feelings
I just wanted to clarify that Qin most probably was more curious and admired Duang rather than having feelings for him

Actually Qin did not have that kind of romantic feelings for Duang when they were in same tutoring class.
Qin more like admired Duang for his kindness (dropping off female friends t station, buying them pads, etc.) and was noticing Duang a lot cause of his good looks (He even said his looks annoyed Qin a lot). So Qin was flustered when he saw that same boy he looked at looking at him now and maybe gave him a chance to court him cause he knew how Duang was in a way

There are some things that haven't been properly addressed and the director even said that Qin's POV still has some things to be resolved, so yeah there is a reason why it's 12 episodes cause we still don't know what those episodes have.