Okay, I guess we are not only in the "matured" dramas here:
Oh, My Venus - I didn't see it, but read a bit about it.
Mars - I have seen that one not a Kdrama though, but no worries.
My Girlfriend is a Gumiho ... I've watched a long time ago.
I think you probably might like these, but I have no idea how many dramas you already watched of them, anyway here we go:
-Marriage not Dating, Nine - Nine Times Time Traveling, Faith, Autumn's Concerto, Master's Sun, The Greatest Love, W, Splash, Splash Love, Bride of the Century, Fated to Love You, I Hear Your Voice, Kill Me Heal Me, My Love From The Star, ...