Do-jin lost interest in all other women after a one-night stand with Yu-young. He just cannot stop thinking about the woman that he met that night, and will do anything to see her again.

Was it a one-night stand after effect? Dojin Yoon is unable to get turned on after meeting that girl.
It's as if she has cast a spell on him, his body was numb, She was the only remedy to free him from the spell
Yuyoung Ha, the mysterious woman who left a strong trail behind from the very first time they met.