Right. Now they are adults but He Tian still acts childish, obsessive and is a push over. It used to be quirky but now it became so in your face annoying because he actively avoids having serious conversations and doesn't take Mos feelings seriously. It doesn't help his case that Mo has went through so much character development and is way more mature than him now
Ngl, I think he just really doesn't wanna talk about what he went through while he dissapeared. You see even in his middle school days, he hides behind a facade of playfulness when serious shit is going on in the background. I think most of the stuff he does in these last handful of chapters is just his way of showing how much he missed Mo. He doesn't wanna talk about the serious shit, he just wants to hug and kiss all over his man he aint seen in years
I understand that aspect and I agree to a point with your observation. But in the end, he doesn't have to talk about it. He can tell Mo that he had a difficult time and is not ready to have that conversation yet. By doing so, he at least acknowledges Mos feelings without forcing himself to share more than he's ready to. This is what I'm missing here. Being transparent doesn't necessarily mean going out of your comfort zone. Also personally I dislike that he hasn't changed one bit since being a teenager (accept being physically violent... But I think that was a prototype for his early character design)

i used be biggest he tian's shooter but nowadays i need to him to die like you should be begging 9n your knees what are you doing by acting playful around little mo. my mo is so nice he deserves better /hj