I got three good things out of Missing You:
1. Yoo Seung-ho as a villain.
2. The scene in episode 10, I think, where the heroine sees her Mum for the first time in decades. That was just beautiful.
3. The first four episodes, where it's just Kim So-hyun and Yeo Jin-gu being sweet and sad and incredible.

I've conveniently forgotten everything else about the drama 😂

... not even Jingoo trying his hardest could save it. This is no fault of his to be honest; the best actor in the world can't save a bad script. On top of that, the chemistry in HDLL often felt forced, partly due to those scripting and directional issues I mentioned, and it just solidified to me that I find him awkward in outright romantic roles, and that he better suits, to use your wording, grittier ones.

Two for two Jingoo dramas ending in multi-thousand word essays and defenestration. Whatever could be next.

Circle (2017).
Circle. The darling lauded by the masses to me for several years, the supposedly mind-bendingly excellent, best kdrama sci fi to ever exist, that had been on my watchlist ever since it's airing.
I finally picked it up in September 2019, and at this point I’m sure you can guess what happened.
I didn’t like it, I wrote 4000 words on it, (which is again only the tip of the ice berg of my problems with it!), and I threw it out a window. Or thereabouts.
(And boy oh boy, if I wasn’t with the last two, am I in the unpopular camp with this one.)
In inadequate summary; I found Circle to be too much plot, mostly predictable, and not enough character depth.
However, Circle did have a pairing with Jingoo I did actually like. I liked him with his maybe-maybe-not-an-alien maybe-maybe-not-girlfriend. I thought that understated relationship was one of the better parts of the show.

I also watched Tree With Deep Roots (2011) in 2019, which is excellent and one of my favourite shows. Jingoo also appears in this, but his part is merely a guest role, and not a lead. I thought he did well as the young Ddol Bok though.
(Thankfully, one of the few wise decisions I made in 2019, was to NOT start My Absolute Boyfriend)

And then finally we have Beyond Evil (2021).
I watched this whilst it was airing, and whilst I don’t love it as much as everyone else appears to, I did enjoy the beginning of it especially, and it is to date my least hated of Jingoo’s leading role dramas. Unfortunately, it lost me a lot in the latter half; I got bored, I did not get much out of it, and I think I would say I found it lacking overall, particularly in some areas regarding character development.
Although it wasn’t really romantic, I did find myself enjoying his character’s interactions with Jae Yi, though, and often wish there was more of them, and that combined with his role over all, once more confirmed how I feel about him as a romantic lead and what kind of roles I think suit him best.

Thus, (despite BE technically breaking the run because I didn’t dislike it enough to write thousands of words on it) Jingoo and I seem doomed to dance in and out of this cursed relationship with his shows.

For me, his portrayal of Yi Heon still remains his best work. And it is because of that portrayal I still keep trying his shows, despite said doomed relationship.

IRY is in my top ten dramas, but Suspicious Partner was physically painful for...

... me to finish.
The IRY writer has potential therefore to write a role for Jingoo that really suits him, but the premise of it so far in terms of the romance angle somewhat concerns me.

Ergo I will start this, at least, and take what’s coming to me.