He has a doctorate in cutting-edge and high-end subjects from a key university and is about to go abroad for further study; she is his junior sister who has just started graduate school and is studying in his research group. To her, he is called Senior Brother, and he is actually a good mentor and idol; to him, she is lively, cunning, and annoying. But what happened to her boyfriend? It was inexplicable and strange that he didn't like it. Forget it, it's time to leave, what are you thinking about? But I am stuck in an emotional swamp, how to extricate myself.