I get it. His mom repress his feeling, emotion, opinion.

And as a result some of his memories too it appears.

And thus he is acting every day of his life, displaying fake emotions, but there are moments when he stops, and the people who witness this become shocked because of the drastic change in personality, and the expression on his face.

Yeah, thats right, it occurs change his personality, memory, his expression.

Poor him.

Yeah.... He can't deal with people in a real life way unfortunately.