暗戀哥哥的好朋友多年，他是出了名的桀驁不馴隨性放蕩，那天他一句玩玩而已沒動真心讓她徹底清醒，後來她試着和別的男生接觸，可浪子校草卻又嫉妒到發瘋，把她圈緊懷裡紅着眼求和：不分手好不好#甜宠 #先婚后爱

A young girl expresses her youthful crush. Three years later, she is determined to get into the same school as him. A comical collision leads to them accidentally swapping phones, revealing shared passwords and the girl's secret crush diary.

The girl, unable to swim, is rescued by her crush, He Xilou. She initially hides from him but eventually thanks him. He Xilou challenges her to repay him with a date, hinting at his own romantic interest while navigating public displays of affection and misunderstandings with other potential suitors.

The girl enrolls in the same university as He Xilou, only to find him as a teaching assistant in her class. Their frequent encounters spark rumors and jealousy from others, particularly from He Xilou's friends who notice his changing demeanor. A public proposal to the girl by another student leads to He Xilou's intervention and a public display of protection.

As their relationship navigates the university setting, the girl is mistakenly believed to be dating another student, Song Wenzhou. He Xilou shows subtle signs of jealousy, while the girl tries to understand his true feelings amidst public rumors and the appearance of Qin Shuyao, who is believed to be He Xilou's childhood sweetheart.

The girl becomes increasingly confused by He Xilou's actions and comments, especially after seeing him with Qin Shuyao. A misunderstanding amplified by social media suggests He Xilou and Qin Shuyao are a couple. Driven by her feelings and encouraged by friends, the girl confronts He Xilou, leading to a revelation about his family and his true feelings for her.

He Xilou clarifies that Qin Shuyao is his sister, born to the same parents but with different surnames due to their parents' separation. He confesses his long-standing love for the girl, revealing he has been secretly observing her. They officially become a couple, celebrated by their friends.

The couple embraces their new relationship, although the girl still finds it somewhat surreal. He Xilou's brother returns to China for his birthday, creating a comedic situation where the brother is unaware of their relationship. The couple faces the challenge of revealing their secret to the brother and seeking his approval. The brother, upon learning the truth, expresses his concern for his sister's happiness but ultimately accepts their relationship.