basically fl has to be convinced for a long time to finally like the ML back.

Romance is a Bonus book - literally takes her forever to realize what she feels lol  

 Lou:

Romance is a Bonus book - literally takes her forever to realize what she feels lol  

Thank you a lot but i already watched it 

That's a pretty common theme.  I can think of dozens.  

A few favorites are 

Happiness

Mr. Sunshine

Mad For Each Other

My Unfamiliar Family  (One of the best friends to lovers portrayals)

Thank You  (a young Jang Hyuk and Gong Hyo Jin)

Another one that is precisely what you requested but I hesitated to recommend it because the FL is so frustrating is the Japanese  I Don't Love You Yet

  • My Name
  • Our Beloved Summer
  • Alchemy of Souls

Love is sweet: FL sees ml as bully but in reality he likes her. It took quite some time to realize her feelings