I Regret Asking for a Breakup

The cover isn’t great, so please don’t hate on it. After his parents remarry, the protagonist, Wu Chen, gains a stepsister one year younger than him. She is sweet, adorable, considerate, and well-behaved. In high school, Gu Wuchen is a group leader and discovers that one of his pretty female classmates has a habit of smelling socks. He helps her improve her grades, and she becomes deeply dependent on him, with a strong possessive streak. As they spend more time together, she succeeds in winning him over. But their relationship is far from smooth: the girl’s self-centeredness eventually wears down Gu Wuchen’s patience. They break up, and he is left heartbroken.