My Dream K-Drama Couples!

Korean Actors and Actresses I want in a romance drama. But only/hopefully in my kind of drama (Action/Thriller, Mystery Romance... NO/or ONLY a bit of comedy). Ilike thrilling -romance = serious relationships NOT comedy+melodrama). Romance development: preferably a slow build up or with lots of tension, growing feelings while going through things together/helping/protecting each other (the plot (Thriller/Action/Horror, hardships, danger...  whatever)). You get it right? :-)) W - Two Worlds is the best example. Except there were small parts which were too sweet/shallow for my taste. They could have used the time for letting the feelings/relationship grow deeper/more serious or something.