Trick- it has three seasons, three tv specials, and I think four movies. They are always just friends. Romance is hinted at but never happens.
Stranger- Their friendship is one of the best parts of the show.
Woody Sambo- They hate each other at first but quickly become friends, it does turn romantic.
Good Doctor- They are friends for a long time, and the male lead falls for her first. She's a bit blindsided when he confesses and it takes her a while to think about her own feelings for him.
Smile, Dong Hae- It's a family drama, and while it is long they are friends for a good chunk of the show, and later develop feelings for each other. It has 159 episodes around 40-35 minutes each.