I don't live-watch, so I usually witness the furious outcry when a drama ends disappointingly.
I adjust my expectations to the lowest level possible, and it helps a lot.
Sometimes it acts as a protective cushion, absorbing most of the shock and letting me shrug it off.
Sometimes it makes the ending good because it was not the worst possible ending I was expecting.
Sometimes it helps me to appreciate the good scenes leading to the ending more because I know they won't last.
This method is also especially helpful in case of open endings.
Although there are dramas that are so good that no amount of warning is going to help me get over a bad ending. My heart will rage for a day or two, and I will quickly turn to Chief Kim, or Lookout, or some other tried-and-true love to make everything ok again.

I am usually not too bothered. I usually enjoy the journey and don’t expect much. Very rarely dramas jolt me with their ending. And thanks to my amazing memory I forget them all soon 😅
It also helps that I move on to the next drama quickly.

How do I cope? I noticed that I move on to the next drama.
Of all endings that haunt me, Monthly Magazine Home and Oh My Ladylord grates me because it never had to end that way(MMH) or be an episode after episode of 1 step forward and two steps back (OML).
So if it's a live watch whereby I read the recaps before the ending, I don't bother watching the ending until I see fit(Bossam, OML, MMH etc) and a bunch of others. Sadly a bulk of them remain unwatched (Bossam, OML, etc). If it's an ending I watched before reading the recaps, I blow a fuse properly. Give me a week or two and I'm back in line. But, if there's any allusion to that movie again, I'll be back to blowing fuses.

Why oh why is a pic of 2521 featuring this article?!? That ending made SO MUCH sense I will go on defending it forever.

If bad ending here means it’s subjectively bad or disappointing for me, one of it is definitely Alhambra. Why in the world did poor dimpled Hyun Bin had to suffer that much for such ending? This and the name Emma will forever haunt me. As a result, I try to erase the whole memory in my head.

Another one that came to mind was when Dalmi chose Dosan in Start-Up. Though I agree with a comment on YT that Suzy always make questionable choices when it comes to men in dramas, I didn’t especially hate it because it was easy to see who she would choose in the end. Instead, I developed extreme SLS and have forever since become a fan of KSH.

Another one isn’t about the ending per se but the direction and execution of the last couple eps of <A Business Proposal. It was disappointing to see so many characters acting out of their character. So instead of it being listed as one of the all-time favorites, it’s become a distant memory.

I guess my mind gradually delete the existence of disappointing dramas (1 and 3) or I’ll be rewatching it to see if I was too biased to notice certain things that would make the drama watchable and the ending make sense (2).

I was expecting more "go on a rant on DB/Reddit/Twitter to express my utter outrage at the ending" because I've definitely been there, done that 😭.

There is ending and ending :p

In one case, I can see the drama slowly choosing an end that I know I won't like or make me feel not completely satisfied. For example, lastly, Mental Coach Jegal, the love story was hinted but still the end I was hoping they won't choose it. Or Business Proposal, the arc with the grandfather was pretty disapointing. So when it's slow, I kinda loose my interest for the drama little by little.

In the second case, it's pretty sudden like in Because it's my First Love or Monthly Magzine Home with the FL who left without any warning and logic. In the first example, the rest of the drama was really good, so I still keep it as good memory. In the second example, the whole drama was pretty bad, so the end was just the nail on the coffin. If the drama was really good, it make me feel very frustrated but in the long run, I will just remember the good moments.

So this topic comes up right after ep 11 of One Dollar Lawyer!? That's just a coincidence, right? Right?

I cope largely by being snarkastic and giving the final week a low score. And I'm not optimistic about 1$L.

It probably is a given that more often than not unfortunately a kdrama’s ending will be disappointing.
There probably should be a rating system for endings and as a suggestion 1-5 with 1 being great/excellent and 5 being a spectacular crash landing.
Just picking two dramas over the last couple of years, for an ending rating of 1 (great/excellent) I would award it to ON THE VERGE OF INSANITY (2021) (Viki US).
For an ending rating of 5 (spectacular crash landing) I would award it to DO DO (2020) (Netflix US).

When I first got into kdramas, I remember reading somewhere that bad endings were common in them. I was shocked that that seemed to be the prevailing wisdom, because what first draw me to dramas was that they all seemed to end well--if not happily, then at least in a way that left one hopeful rather than crushed.

In recent years, though, I've found myself more disappointed in certain endings, but I wonder sometimes if that has little to do with the dramas themselves, and more to do with me being more active on-line in my discussion and info-seeking about them.

For example, I watched "Because This is My First Life" after it aired and didn't really pay attention to the online chatter about it. I was a little surprised at the first part of the end where the FL suggests divorce, but I just took it in stride as a typical plot twist that happens at the end of a romantic drama to force a separation and then give us a big reunion. So it didn't poison my overall love of the drama. But later, when I read a bunch of references to pretty intense anger over that ending (or the lead-up to the ending) I was taken aback. I remember thinking: It wasn't that bad, was it? Did I miss something here?

Similar thing happened with "Mr. Queen," which I watched slightly after it aired. I knew there was some general disappointment with the ending so I braced myself before watching. I certainly felt that the King's line about something being missing was a bit of an own goal on the writer's part in that it would have been so easy to add a few lines earlier in the episode that showed us that the original Queen was able to integrate aspects of the modern man who inhabited her body and become the fully realized person she always wanted to be. But again, I still loved the drama, and was taken aback by how many viewers felt that one line had utterly gutted them and ruined the entire love story. To me, the writer was clearly intending that more as a funny moment, not as one of heartbreak and sadness. Maybe it was a mis-fire, but I'd never say that ending was terrible, or anything like that.

But then came 25/21. This was maybe the first time that I can remember that an ending really disappointed me. I understand there are those who feel just as strongly that it was the proper ending. This is certainly a testament to how well written and special the whole drama was. Nevertheless, that ending was not at all what I hoped or wanted to see, and it did undermine the pleasure I had felt in the drama up until that point. My stomach hurt, and I felt sad while watching the breakup and aftermath. And due to that ending, I know I'll never rewatch even parts of 25/21 even though it's objectively still one of the best coming of age dramas ever made.

So how do I get over bad endings? The same way I get over most things: try to not think about or revisit them. It mostly works.

I think this is a great topic and there were probably a few contenders for the cover picture🤣. I always have a number of dramas on the go at various stages so I just move on to the next episode of one of the others that I am watching at the time.

I think it depends on how good the drama was up until that ending point. If it feels like the original writer was kidnapped at episode 14 and no one was prepared to pay the ransom, so the assistant’s assistant had to to finish it that can have more of an impact than if it was going downhill gradually from episode 8.

I have had conversations with the screen, if it’s airing I have shared my thoughts in the comments section but usually that’s when it goes downhill during the season. I often do my own rewrite which is easy to do when I have had access to the material and not having to make it up from scratch. On the whole it’s light hearted because its like back seat driving or telling the ref what the decision should be it’s not my day job and I am not personally invested in the drama. I remind myself that it was my choice to watch the show as a form of stress release, and there are far worse things that can happen than feeling I wasted my limited time watching a disappointing drama.

I don't feel that bad with the ending of 2521, I feel it was not that unexpected 🤣

As for CLOY few years back, I think it was bittersweet.

If there's an ending that made me feel 🤬 this year, it comes from a non kdrama, there's this lowkey(but good) costume drama recently that had the audacity to kill off both my favorite characters in the end it made me feel so ugh.

How I deal with these 'bad endings' normally just rant about it together with other viewers on where I found suitable or where there's open discussion mdl/reddit/db/twitter/fb, and move on to next dramas (usually watching few at once)

With a bad ending, I ask why? Why did writer/director end the story in a bad, weird, awful way? If there is some explanation (even if I disagree) I will accept it. If there is none or the showrunners hide, then I will criticize as necessary to ease my mind.

Avoiding live watching. Although I will admit it's hard to always stick to this rule, I have found most of the awful endings I've encountered were in shows I watched while they were airing. And for the ones I watched after they aired, I at least had time to prepare myself for the fact that something alarming (or at least controversial) was heading my way.

I try to manage expectations.

I've watched enough kdramas and non-kdramas to know that disappointing endings will happen to a majority of the things I watch. I acknowledge that it's just really, really, really hard to write a satisfying ending. Sometimes writers are still writing while the drama is airing and they're under deadline to produce an ending in a few weeks.

Of course, with pre-produced dramas, I rage a little bit.

I also remind myself that a disappointing kdrama ending is nothing compared to the ending of How I Met Your Mother. It was 9 seasons long and I started watching when season 2 aired and even bought DVDs.. That one hurt for a really long time. I still rewatch, but I skip the final episode. The creators released an alternate ending, which was beautiful even though it would leave some major loose ends, but it still hurt that it wasn't canon.

For kdramas, I mostly move on to a new drama unless it's was terribly bad.

Well, there are disappointing endings and then there are awful ones.

Disappointing: Little Women (a bit, because Kim Go-En's character ends up all alone), Alchemy of Souls (just an awful place to end the story and I hope part 2 brings us to a satisfying conclusion), Yumi's Cells (both seasons, because they each end with a breakup), Jirisan, Nevertheless, Sisyphus, LUCA. Those are merely disappointing.

The truly awful are the ones where you're left saying "WTF did I just watch in the last episode" - like Marry Him if You Dare, and (an oldie but still the winner/loser in this category) Fashion King. Where you feel like the last episode tried to suck all the life out of the viewer, or at least leave you severely depresses.

IMO Alhambra falls somewhere between the two. If I watched it again, I might find the ending making more sense, from a plot perspective.

There are a few possible cures for the ensuring rage - 1) Immediately binge a really great KDrama, 2) if you have a currently airing or recent KDrama that you really like, focus on it instead, 3) Turn off the TV/Computer and get outside or 4) read a good book...

For me, Noble Idiocy seems to play a part in the most egregiously bad endings.

My negative reaction is usually in proportion to how much I was enjoying/had become invested in a drama up until the bad ending. It often involves shouting at the screen in disbelief (“Really, Show? REALLY?”), and then muttering angrily to myself for a day or so. Dramabeans Therapy—sharing the pain with fellow-sufferers is a huge help!

The worst offenders, in my estimation:
—Do Do Sol Sol La La Sol
—Doctor John
—Something in the Rain
—Monthly Magazine Home
—Start Up (gave up on this one as soon as it became clear which guy would end up with the girl.)

Gosh, doesn’t everyone just run right here to see what Beanies are saying? I couldn’t get here fast enough when Do Do Sol La ended, was still yelling and cursing at the screen 🤣

Oh, K-drama endings. Always that huge possibility that you will be left with wft??? above your head and a hole in your stomach after the last credits roll, even when the ending wasn't the worst. It even makes watching somewhat masochistically exciting. <3 I am happy to report that I didn't find the MoA ending bad for some reason, I was probably in a very alert and prepared state of mind while watching. In BTIOFL the FL started to annoy me somewhere around the middle of the series so I wasn't that taken back with the ending. Also, a slight delay in live-watching Scarlet Heart and Pretty Noona while checking recaps saved me from finishing these two (left the SHG 4 eps before the end, lol). But generally, I think I somehow manage to avoid picking dramas with really really shitty endings. Except for Hwayugi. That "end" was just so awful at so many levels that... I cannot even.

If I'm not live-watching and have access to the weecaps, I bail if things start going south. I did this with Mental Coach Jegal once I found out about the love story introduction. Couldn't face it.
If I'm live-watching and keep hoping things will improve, or they suddenly take a turn for the worse, I rant. And then bail. Life's too short.

I'm OK with open endings, rushed endings, unhappy endings, unfavorable ship endings. I didn't even mind the CLOY ending. There really was no good way to end that one anyway. Sometimes the happy endings are too over the top for me (too many candles and fireworks always makes my eyes roll). There is one, and only one show whose ending was so awful it made me feel completely unhappy with the entire drama and that was Do Do Sol Sol La La Sol. I do however prepare for difficult endings and am happy to read spoilers to make sure I'll be prepared!

I generally avoid high stakes dramas to be honest. If I’m feeling like suddenly I am going on an emotional rollercoaster, I get off earlier than the end. I still haven’t finished the last four episodes of Alchemy of Souls because it went from lighter to high stakes. I also almost always avoid watching 13&14 until 15&16 are there because things always go downhill in 13&14 -the romance has the biggest setback and the baddies always momentarily triumph. I prefer watching it all as one final arc, and it’s less stressful.
Even though sometimes I get spoilers, I do like to read comments here when I am live watching to get a sense of where the drama is going. I can often gauge whether I want to watch, wait to see if the drama evens out, or just read the recaps.

Bad endings always remind me of the unfinished horse drawing meme.

Bad endings don't ruin good dramas for me because I just rewrite the ending in my head, so I can still love dramas with a disappointing ending.
Reply 1988: I was Team Jung-hwan, but it's still one of my all-time favorite dramas.
SKY Castle: I hated the happy ending and wished the killer had been a twist but still love the drama.
He Is Psychometric: The writer made Sung-mo the culprit and killed off his love interest, but it's still one of my all-time favorite dramas.
Business Proposal: I was so disappointed Grandpa refused to accept Ha-ri, but it's still one of the best rom-coms of all time.

However,
Twenty-Five Twenty-One: The drama wasn't ruined by its disappointing ending or the OTP not ending up together; it was ruined by the god-awful present-day storyline and adult Hee-do.
Do Do Sol Sol La La Sol: The drama wasn't ruined by Joon faking his death and returning five years later; it was ruined as soon as Joon became an underage minor high school senior.

Reading through the comments, I think i'm on board with a bunch of the commenters:

Do Do Sol Sol
Start Up
Monthly Magazine Home
Oh My Landlord
Because This Life is My First

Really hated the endings which ruined what was otherwise a decent watch. The one that seems most egregious is Monthly Magazine Home which was a fun, not too serious show and turn it into a Jung Somin special of leaving her man at the end of the show for not obvious reasons.