I recently fell into this new world of K Drama. I think I like them more than Taiwanese dram. My secret Romance was my first K drama , followed by Legend of Blue Sea. Please suggest some good Korean Romance thriller dramas. 

Since you are looking for romance with thiller genre, and seemed to liked Legend of the blue sea, i recommend:

  • Healer
  • You who came from  the stars
  • Goblin
  • Masters sun
  • Queen inhyuns man
  • My GF is a gumiho
  • Pinocchio
  • Oh my ghostess
  • Moon that embraces the sun
  • Kings 2 hearts

I second Healer

  • Naked Fireman (it's only 4 episodes but a really solid short thriller/mystery/romance drama)
  • Hello Monster
  • Lawless Attorney (still airing, but suits your request for a thriller/romance well)

Other good romance (more traditional rom-com):

  • Suspicious Partner
  • I'm Not a Robot
  • Rooftop Prince
  • A Poem A Day
  • Strong Woman Do Bong Soon

More KDramas you must watched:

  • Descendants of the Sun
  • A Beautiful Mind
  • W
  • Oh My Venus!
  • Coffee Prince
  • An Innocent Man
  • Jelousy Incarnate

If thriller and/ or romance is what you're looking for then:

  • Misty
  • Save Me
  • Money Flower
  • Secret Love Affair

Scent of A Woman - Excellent Main Cast and Supporting Cast (Uplifting Drama - one of the best)

Coffee Prince - Deserves the accolades (Excellent Main Cast and Supporting Cast)

My Lovely Sam Soon - First half is the best, still excellent drama, the ending is good, done with sincerity.)

The Legend of the Blue Sea - You've already seen this one :)

Any of the above are worth your time.

Quite alot of the time the main cast are good, or maybe not in some cases; but the supporting cast are not developed enough in my opinion, so definitely try the above ones.

Black & Empress Ki

My personal favs:

Healer

- the first couple of episodes can feel a bit slow and confusing, so don't let it stop you, there are many good reasons why Healer is one of the most popular dramas out there

- mix of investigation, drama, comedy and romance (btw definitely the best romance I've ever seen in any drama)

I'm Not a Robot

- cute and fluffy but surprisingly deep and thoughtful at times

- 30min long episodes - handy when you have only so much time during lunch breaks/evenings

Queen In Hyun's Man

- time-travel romance with a clever male lead from Joseon era who adapts to the modern world and uses his newfound knowledge when he goes back in time

- very few plot holes (which can be rare in fantasy dramas...), satisfying ending!

The Master's Sun

- solid mix of horror (the female lead sees ghosts), romance, drama and comedy

- fantastic chemistry between the leads

- downside: uses some clichés, some have a surprising twist though

Hope this helps a bit! <3 Happy watching!

Try

- W two worlds 

- You who came from the stars

- Strong woman do bong soon 

 Czakhareina:

Sin you are looking for romance with thiller genre, and seemed to liked Legend of the blue sea, i recommend:

  • Healer
  • You who came from  the stars
  • Goblin
  • Masters sun
  • Queen inhyuns man
  • My GF is a gumiho
  • Pinocchio
  • Oh my ghostess
  • Moon that embraces the sun
  • Kings 2 hearts

Thank you very much. Heard good reviews about Goblin , Healer , Oh my ghostess.. Now I have my Saturdays planned. 

 neo:

I second Healer

  • Naked Fireman (it's only 4 episodes but a really solid short thriller/mystery/romance drama)
  • Hello Monster
  • Lawless Attorney (still airing, but suits your request for a thriller/romance well)

Other good romance (more traditional rom-com):

  • Suspicious Partner
  • I'm Not a Robot
  • Rooftop Prince
  • A Poem A Day
  • Strong Woman Do Bong Soon

Strong Woman Do Bong Soon was super awesome movie. Hmmm, suspicious partner - ;)

 luckygirl110110:

More KDramas you must watched:

  • Descendants of the Sun
  • A Beautiful Mind
  • W
  • Oh My Venus!
  • Coffee Prince
  • An Innocent Man
  • Jelousy Incarnate

Thank you :) ...Descendants of the Sun is a war based movie no?

 ShotaSidePart:

If thriller and/ or romance is what you're looking for then:

  • Misty
  • Save Me
  • Money Flower
  • Secret Love Affair

Currently watching Secret Love Affair & Black....  :)

 Heavenly6:

Scent of A Woman - Excellent Main Cast and Supporting Cast (Uplifting Drama - one of the best)

Coffee Prince - Deserves the accolades (Excellent Main Cast and Supporting Cast)

My Lovely Sam Soon - First half is the best, still excellent drama, the ending is good, done with sincerity.)

The Legend of the Blue Sea - You've already seen this one :)

Any of the above are worth your time.

Quite alot of the time the main cast are good, or maybe not in some cases; but the supporting cast are not developed enough in my opinion, so definitely try the above ones.

Thank you Heavenly6 for the reviews.  I love series where there is a good spark between the main role actor / actress, where they keep us on couch forcing us to watch next episode back to back.