Dramas Without Love Triangles

a couple that come to mind are ode to joy season one, honey and clover the taiwanese version ( it far outstrips the Japanese version which is very rare), life is beautiful ( it has a lot of great stuff, and has no makjang! tons of events tho and awesome romances everywhere.) Whats up. there is enough to keep you busy for a week or two.  

what about watching a completely different genre of drama then, where you wouldn't have to worry about if the main couple stays on? 
most of the kdrama don't really go that deep in the triangle scene. they just show it lightly, or for a little bit and then the focus of the drama shifts somewhere else and then main couple gets back or something. at least that's what happened in the dramas I've seen so far. 
here are some recommendations for romance drama: 
Cunning Single Lady
Falling for Innocence(triangle but....)
Goblin
Healer
High-end Crush
It's Okay, That's Love(i think you'll handle it)
King2Hearts
Marriage Contract
Miss Korea(this one too)
My Girlfriend is a Gumiho
Nine: Nine Times Time Travel
Noble, My Love(watch this and you won't have to watch My Secret Romance)
Queen In Hyun's Man
Radiant Office
Second to Last Love
Shopping King Louis
Something About 1 Percent
The Full Sun
The Girl Who Sees Scents
The Princess' Man
The World That They Live In
You Who Came from the Stars

Legend of the Blue Sea
The K2  - I had friends who said there was a love triangle but I didn't think there was--
High-End Crush
The Guardians - Only just started airing but it isn't a romance, so I'm not expecting a love triangle or any romance at all- 
Tunnel - I haven't finished it myself but I don't see a love triangle sliding into the script so

(these have either only a little romance or none at all, but still they're really good with no love triangle.)
Voice 
White Christmas [drama special] 
Signal - People could probably argue that there was a little love triangle during the drama tbh but nah


(It's been awhile since I watched these, but from what I remember, they didn't have a love triangle or it wasn't a major love triangle that y'know,, got in the way)
Blood 
Remember - War of the Son
Yong Pal
49 Days
Page Turner 

I would second Master's Sum, one of my faves. 

There also a few other slightly older ones I  can recommend -

Arang and the Magistrate
Dal Ja's Spring
Ho Goo's Love
Oh my Ghostess
Sungkyunkwan Scandal
Coffee Prince

All of them have a bit of a triangle at some point or other but never so much so that it has the potential to affect the main couple.