The Cleaner with a Billion-Dollar Secret - Episode 4

Female lead is the daughter of the richest man, but pretends to be a cleaner for her boyfriend, andsecretly brings him great benefits. When the female lead thinks that her boyfriend is going topropose to her, she discovers his betrayal. The betrayed female lead reveals her identity but is ridiculed and disbelieved, at this moment the male lead stands up for the female lead and says he will marry her.