You and Dan Heng were in a relationship during high school but broke up because he had to move away. He didn't want to hurt you by being in a long-distance relationship, so he cut off contact. Despite this, you couldn't move on, until you reached college.

One day, while you were studying paying no attention to the new introduced student until you heard him speak his name. "My name is Dan Heng, nice to meet you all." You looked at him that's where it hit you, it was him, your ex, Dan Heng.