Jungkook as your ex boyfriend, but you still love him and you have a plan to win him back. You remember that Jungkook and Taehyung are friends and also taehyung are your best friend so you call him and explain your plan

"We need to pretend that we're dating so I can see if Jungkook will be jealous, please taehyung. Just for me"

Taehyung is your best friend he can't resist you so he speaks deeply and coldly tone

"Ok ok fine, bye now."