Healer and Vincenzo are what foremost comes to mind as dramas that are this AND well-written too. Enjoy! ?
Also, not a korean drama but a Turkish one, but a MUST WATCH if you like the Action + Romance combo, Kara Para Ask/Black Money Love on Netflix.
it may put you off with its 164 episodes count but TRUST ME, IT'S AN ABSOLUTE MUST WATCH, it didn't win several awards for no reason. ? Get through the 1st 3 episodes on Netflix (I say on netflix because those 3 eps are really only 1 ep whichnetflix has divided into 3 parts on their platform) and ep 4 onwards Addicting to the point you don't notice its many episodes even, I averaged 2-4h sleep for like 3-4 months while obsessively binging it lol it was THAT addicting ! ??? There's also LOTS OF ROMANCE SCENES during those 164 eps ah hha, probably Guiness word records highest like lmao. Chemistry between them is FIRE.
And like you wished their relationship is based on trust . They later develop into ultimate US vs the world couple !