Both Bo Ah and Hyung Sik came from different backgrounds. When they meet, they click instantly. They become inseperable. After a year, Hyung Sik becomes a completely different person. He grows colder to Bo Ah. Shortly after that they break up and Hyung Sik starts seeing other people. Bo Ah is left heartbroken and attempts to forget Hyung Sik. She does with the help of her new boyfriend, Jackson.

This is based of my favorite Japanese drama. KOIZORA.