“Date me for 5 years. Then I'll propose and marry you.”
And they kissed.
And they stayed oblivious to the hardships that come with any relationship.
And soon, 5 years had passed like a blink of an eye.
All but one had remembered their promise to each other.

-------------------------------------or------------------------------------

Jungkook doesn't realize all Jimin does for him.
All Jimin wants is for Jungkook to propose to him.
Taehyung shows up and brings out the love Jungkook had forgotten all about (by trying to get back together with Jimin and making Jungkook jealous).