I would love to hear suggestions for dramas that features the male lead falling for the lead female fast. It doesn't have to be in the first couple episodes, but within the first 4-6 episodes would be great. 
I would like the lead male to show deep interest in her by half way through the drama and him actively trying to be with her (even though she might be resisting)... 
Something like Secret Garden (... or Heirs), where he pretty much showed how much he liked her at the beginning (like a quick obsession). It didn't take him a while (over half the series) to develop feelings; it was quick. 
I just saw your drama list, and I can suggest you the Descendants of the sun this absolutely fall for what you asked for ^_^ .
If you liked Secret Garden, I'd suggest (where the male lead actively pursues the girl/shows interest)
I Hear Your Voice
Boss and Me
Cheer Up!
Hana Yori Dango
Devil Beside You- I think he falls for her the first episode.
Cruel Romance
Lady and Liar (He falls hard and fast and accepts it happily)
Far Away Love 
Protect the Boss
Also ... Noble My Love     &      High End Crush
The Lady and The Liar
High Scho0l King of Savvy
Me too, Flower!
Cheese in the Trap