Emotional romantic drama with a happy ending

Hi! After a few more lighthearted kdramas, I'm ready to dive into more emotionally-intense or serious shows and would love recommendations.

Think Dr. Slump and Crash landing on you rather than Business Proposal and King the land: I loved all of those, but the former two are more dramatic and less comedic.

In Dr. Slump I loved that it delves deeper into the emotional rehabilitation of its leads after their traumas, and Crash Landing On you adds a little action and suspense (in addition, to, of course the north/south tension that is more political as well). They are both also very well written, which is something I feel is somewhat missing in the more comedic shows.

But it has to have a happy ending, I'm not cut out for anything else... And, of course, serious chemistry and intense commitment of the ML are always welcome.

Other shows I've seen so far, other than the four mentioned: Love Next Door, Her private life, What's Wrong with Secretary Kim?

I loved them all, but the latter two exemplify the more lighthearted vibe that I'm not looking for at the moment.

Thank you!