'Mrs. Jin, She's Incredible' fits the plot you described! The female lead, Su Su, disguised herself as a man and sneaked into the boys 'school to find her fiancé. Because of her irritable and arrogant personality, she attracted the interest of the iceberg school hunk. The two of them got to know each other through fighting. In the end, they became a cohabiting couple and became the favorite of the boys in the school. I hope you like this fairy's recommendation. Muah ~😗