Jungkook just wanted to steal some expensive stuff from the apartment of the girl that he's been eyeing for a week but, instead of stealing he got himself an instant girlfriend.
Chaeyoung is invited to her ex's wedding and there's no way she's showing up alone. When Jungkook receives an offer to be Chaeyoung's fake boyfriend for the day, he accepts it for at least two reasons; first, he's damn broke and second, he's as lonely as the old landlady with 99 cats. Or perhaps, lonelier.