She sacrificed a lot for him and never asked for anything in return.
He knows everything but has nothing to offer in return.
She was aloof, but she was forced to smile.
He was gloomy, but he laughed with her.
Domineering social heroine × sinister and gentle male protagonist
She only didn't smile in front of him, and he only smiled gently in front of her.
Concept: Companionship is the longest confession of love (?)