I think He Tian feels hurt when anyone rejects him because he's extremelly lonely... but I don't know if he realizes how humiliated and bullied he has been making Red feel... He Tian seems someone more experienced, tough, and less naive than people his age usually is... so maybe his perspective of how rude he is to Mo is distorted (I mean, I'm surprised He Tian wasn't expecting a negative reaction from Mo... but because he has more experience, he seems to believe a kiss is not such a big deal... so maybe he also thinks his teasing is not so terrible, because he has seen more violent things? this is hard to explain...)
It is a complex thing, He Tian has got going... But yeah. I hear yah...
I mean, it's fun and crazy. Teasing is okay.
But you can only go so far before someone snaps.
Poor Redhead-kun.
...He Tian looks genuinely hurt though.
I can see he would have some struggle treating people gently...
Especially the ones he cares about.