something like In Time With You, (didn't care much for the k version of it) does not need to be about best friends. Just long time loving. Looking for recs. thank-you 

General and I
Fifteen Years to Wait for Migratory Birds (on the girl's side)
Strong Woman Do Bong Soon
Twenty Again
Bubblegum (haven't watched it tho)
Super Daddy Yeol
Bel Ami (though is not a very good drama)
All of the Reply series. (1997, 1994, 1988)
Goddess of fire - he loved her more than himselfe since childhood but she like him as a brother
Snow white - http://mydramalist.com/1913-snow-white
She was in love with the SL for years.