Epic romance

For me, Healer easily meets all these criteria and remains my favorite series, but I see you've watched it already :)

The Master's Sun has memorable characters and amazing chemistry between the leads. It's a story of a woman who sees ghosts and a man who takes advantage of her talent to solve an old accident... There are however some plot holes here and there and in general, the storyline could be better, but it still got me hooked from episode 1. It's entertaining enough to keep you going.

I'm Not a Robot is a story of a man who is allergic to human contact and a girl who somehow ends up pretending she is a robot he was given... It has a cool cast of characters and the chemistry between the main leads is to die for. Plus points for not magically solving all the issues between the leads and letting them talk it through instead. The plot is solid, a bit black and white though and very concentrated on the main couple (which was fine with me!).

Watch Where The Lost Ones Go, an absolute masterpiece not only in the romance sector but just the storyline in general. Beautiful transitions from future to past. I love how it didn't just explore the happy moments of falling in love but also expressed the pain that can come with it. Honestly missing out if you haven't watched this. Btw, this is a chinese drama.

All of these,I think,fit your criterias. Amazing Chemistry,Memorable characters and good plot.

Go back couple, Just Between Lovers,  I am not a Robot,Coffee Prince,Sunkyunkwan Scandal, City Hall,Goong.

Scarlet Heart Ryeo, Healer, Eternal Love and It's Okay, That's Love

ten miles of peach blossom

princess agent

general and i

Healer

Kill me Heal me

The Greatest Love

Tha Master's Sun

I'm sorry I love you

Just Between Lovers

Pride

Buzzer Beat

Epic love stories...my favorite.

I gave the following a 9 or above and none of these dramas have serious love triangles (thank god). :

King2Hearts- Definitely an epic love story. They're both powerful people from two countries who hate each other...but they're arranged to be married. It's love-hate in the beginning, but the chemistry between them is sizzling.  The side couple also have an epic love story, so that's a plus.  Spoiler: It's a happy ending

Healer- I see you've already watched it, but I'll keep it here anyway for anyone else who's reading this. Healer is a show with an epic romance, an epic plot, epic characters, and an epic cast (seriously JCW and PMY are no joke).  It practically radiates epicness. I've rarely met anyone who's actually disliked the show. 10/10 Spoiler: It's a happy ending

Rebel: Thief Who Stole The People- This one has one of the most epic plots I've ever seen in a drama. Seriously! the son of a servant who was disgraced, tortured, and spit at rises to the top and becomes a strong, powerful leader that now even his old enemies cannot defeat. It's an underdog tale at it's best. The romance is light, but strong. The FL isn't strong, but she's loyal and determined. She's willing to do anything to protect those that she loves. Spoiler: It's a happy ending 

Chicago Typewriter- Very epic. It tells the story of young people with passion and motivation who work secretly hiding from the government. It switches back between past and present which makes it even better. Chemistry between the leads is amazing. 10/10 Spoiler: It's a happy ending