He tried to forget him, since He tian left him without a word. I guess he can't bring himself to throw all those memories away, so he just covered his face and sealed them inside a box.
Yeah, there is something unclear, seems that He Tian went away for a year to start is own buisness, and so probably Little Mo kept that box but was feeling abandoned and sad everytime he looked at He Tian 's picture, so he chose to do something about it. As a way to feel in control, like, '' yes i am keeping this box with all that's in it coz i'm still attached to it, but maybe i am not < awfully attached > to this person who cut me out of their life. ''
That probably means Little Mo awfully missed He Tian and/or resented him for going away and being unavailable for so long. (What do you think ?)
Why did he cover he tian face on all those pics?? Im confused