Your usual K-drama set-up...

A is a very poor girl. For some reason she becomes indebted to one or more rich guys. Maybe she broke something expensive at one of her many part-time jobs or had to go disguised as a guy and was found out. Guy B is rich, good-looking and incredibly nice and honorable. His best friend C is richer, more good-looking and an asshole. He also has a bitchy mother and a bitchy fiancée he doesn't love.
Guy B falls in love with girl A. But for some inexplicable reason A falls in love with C. Drama ensues. C's fiancée bullies A. C's mother forbids their love. A is depressed and drinks, gets a piggy-back ride home from nice guy B. C is depressed and drives around in his very expensive car and then takes a pensive shower.