Why it worked
This video likely performed well due to its focus on a popular K-drama trope (enemies-to-lovers, real-life relationship rumors) and the use of trending audio or visual elements that resonate with fans of the actors or the drama.
Summary
The video shows two individuals, presumably actors, interacting. On-screen text suggests they starred in a drama together, were shipped by fans, and were actually together, with one still obsessed after a breakup.