There Is Indeed Something Wrong with the Romantic Comedy of the Dark Side Observer

[I can see through everyone's disguise, but I can't see through her. Shen Xuyan is an observer who believes in "escape is shameful but useful". He could read malice in the arc of his smile and smell lies in the pauses in his tone - until one day, the pink-haired sweet girl in his class blocked him at the door of the milk tea shop: "Please be my fake boyfriend, and the reward will be a limited edition light novel." He agreed, but he didn't see through the poisonous tongue, guilt, and a brother who was about to break under the sweet smile. When "pretend" turned into "real thing", when "observation" turned into "intervention", the girl who always said "go to hell" asked him with red eyes: "Can you... Stop running away?" And he finally discovered that he had seen through everything, but he had not seen through his own heart. [Single heroine/multiple heroines to be determined, Shura field warning, slow-burning daily series]