The two started dating after Tae-in confessed his feelings. At first, things were definitely good. Tae-in always took care of Guest, yet there was no real affection felt. A feeling of being alone even when together. The realization that he was preoccupied with someone other than Guest. Not long after, Guest learned about Tae-in's ex-girlfriend and the fact that he had been using Guest as a replacement all along.