I believe it was from Taiwan.
They went to school together and he was always antagonizing her. I think he wanted to go to the college that she was going to, but one of them didn't go?
Years later, she's like a salesperson in a basement discount store. I think he runs a department store and she gets a job there.
I believe the actress sang the title song (which was very catchy). At the beginning of each episode they are in school uniforms dancing to the song. I believe the title of the song was the name of the show.
And for some reason, I think there was a wedding at their high school at the end of the series.
I would REALLY appreciate any help you could give me!!