Well there is an obvious answer to this one but I’m not going mention it

School 2015! Yes Yook Sung-jae was best boy!

Most of the chaebol-ordinary person couples.
Also couples that one of them is an angry, rude person toward everyone else except his/her loved one.

Pretty Noona who buys food/Something in the Rain.
They never resolved their issues and just pretended like nothing happened in ep 16!
It’s an OTP that shouldn’t have gotten together imo.

While reading this, I was actually thinking about those couples that I think would last! I guess that shows my assumption that most of them wouldn’t instead of would! (@unit’s idea is brilliant, btw).

These are ones of probably many that I think they would last as a couple. I think Joo Won and Uee in Ojakgyo Brothers, OTP of My Unfamiliar Family, OTP from Uri Husband Mr Oh, OTP of Hospital Playlist, OTP of Start-Up, OTP of A Business Proposal, OTP of Bossam, OTP Love btw Fairy and Devil, OTP of New Life Begins, OTP of Camellia would last as a couple probably for a very long time.

Those that I think might break up at one point: OTP of Run On (I’m not sure if MJ will stick around if there is sth she isn’t happy with ML or their life together. She is a very free spirit), OTP Weightlifting Fairy (Both are very young), OTP of When the Weather is Find (FL too much baggage and unpredictable), OTP of Chocolate (FL needs face her mother and probably cut her off of her and her brother’s life for good or solve this issue somehow) among others.

I'm absolutely sure Lee Bo Young and Lee Jong Suk will not make it to the end of LJS's military service in I Hear Your Voice.

And I know we saw the future in Reply97 and Reply88 but both of the women seemed very bored with their husbands at that point. Which is a shame after what they put us through.

These are shows that I actually enjoyed watching and got the happy ending I was hoping for, but deep down I knew these pairings would never last IRL:

Descendants of the Sun ( not intentionally being snarky here)
Heirs (I see a theme developing here)
A Witch’s Romance

And every “reality” dating show ever.

Go Sera and Gong ( Memorials) will live happy ever after with him trying to figure out what goes on in her head, and being happy by making her smile. I can see them being deeply in love surrounded by lots of kids who just shake their heads while mum and dad go with their (embarrassing) bickering.

I know DoHee and HaeKyung (Dinner Mate), IkJoon and Song Hwan (Hospital Playlist) and DaJeong and YeongDo (You are my spring) will be together forever, because their relations were mature, we’re born from knowing life isn’t easy and neither is love, but if you fight and work for it, you’ll be rewarded with a mature relationship.

There were some OTP that never were and I wish they were, although not pretty sure if they would really work together, like SiMok and YeoJin (Forest of secrets), ChaeRok and EunHo (Navillera), HyunJoo and GaHyun (365: Repeat the year), Eun Jung and SangSoo (Be Melodratic) and JiHyuk and SeoKyung (The Good Detective).

And also there are those couples I totally refuse they are not happy ever after because they are just absolutely adorable together like TaeMoo and Hari (A business proposal), Han Byeol and TaeSoong (Sh**ting Stars), Eun chal and HanKyul (Coffee Prince) or JungRok and YoonSeo (Touch your heart).

I also think

I love search www but PARK mogun and Bae Tami are doomed. They have a fundamental flaw ; they have different ideas of what their lives should be like. I would be shocked if they last five years . One person wants to get married and the other doesn't........It's just a matter of time.

Dr. Ahn Jung-won and Dr. Gyeol in Hospital Playlist.
Song Kang and Park Min-young in Forecasting Love and Weather.
Oh Soo-jae and Chan in Why Her?
Yeom Ki-jeong and Cho Tae-hun in My Liberation Notes.

If I crack my head too much, then a whole lot of OTP's will be a big mess for me cause the dramas forced me to accept the OTPs not that I liked them.

I love these couples, but maybe because they are too young I can't be sure of they will last (but I would love they did): OTP in Weightlifting Fairy, OTP in At a distance, spring is green, almost all the couples in Age of Youth, OTP in Girls Generation 1979, OTPs in My first first love...

Couples that I think could break up for other reasons: It's ok to not be ok, Crash landing on you, Start-Up, The Package, Our Beloved Summer, Go Ho's starry night, Run On, Another Miss Oh, One spring Night, Vivid love...

Couples that I know will be forever happy: Live Up to your name, While you were sleeping, Flower boy Next Door, My unfamiliar family, Into the ring, Because this is my first life, Hometown Cha Cha Cha, Happiness, Secret Garden, 30 but 17, Abyss, Rookie Historian, Shopping King Louis, W: Two Worlds, When the Camellia Blooms, Clean with passion...

In all the other dramas I have watched but I have not mentioned here I prefer to think they will be happy forever, of course.

Boyfriend (a.k.a. Encounter). I disliked this relationship from the very beginning. I didn’t feel any chemistry between them—and not because of the age difference. It really bugged me that Jin-Hyuk kept pressuring Soo-Hyun to get back together; he acted as if he knew what she wanted/needed more than she did herself. At the end, it felt to me that he didn’t so much win her heart as wear down her resistance.

Heard It Through the Grapevine. Two teenagers—a girl from a poor family and a boy from a rich and powerful family—have a one-night stand. They don’t see each other again until he finds out she is pregnant with his child and about to give birth. His horrible parents don’t want anything to do with her, then later try to take the baby away from her. She’s smart, strong, and self-assured, while he’s immature and a bit of a wimp. Hardly a recipe for a successful marriage!

Itaewon Class. Sae-Ro-Yi and Yi-Seo never seemed like a couple in the first place, so I don’t see them staying together, except as friends.

I’m going to throw one of my favorites under the bus: Mr. Queen. While the drama had a HEA ending, I wondered how happy King Cheoljong and So-yong would really be together. Cheoljong fell in love with Jang Bong-hwan, and when he was gone, Cheoljong acknowledged that something was different. I could be wrong. Maybe that’s what the 2 bonus episodes were about; to show they were really meant to be together.

Da Li and Moo Hak are happy. That is the hill I am ready to die on.

Tbh, besides the OTP in Nevertheless and Kiss Sixth Sense, no main couple comes to mind. Generally speaking, out of 16 episodes 8 episodes are wasted on telling the main characters why they should not be together. If by the end, the OTP is still together most likely nothing will break them off.

There are too many, really))) Especially when it comes to older dramas that loved to stretch the "opposites attract" thing to ridiculous lengths.

Wonder why no one mentions the most recent glaring example - Reborn Rich, where the only somewhat functional couple among many was daughter crazy and her pet husband (all their issues aside, it seemed like they genuinely cared for each other and were a team). All while romance between ML and prosecutor lady was DOOMED since the start - they had nothing in common (chemistry including) and would've never last in any of his lives with such polar opposite morals and principles, so it's a good thing that drama ended their story arc with him walking away with not-so-heavy heart.

Oh I once wrote a whole piece on this listing some of the couples (circa 2018 or so) that I thought were doomed. Like Secretary Kim finally cracking and putting death mushrooms in her husband/boss' omelette.

Although probably worse are the ones that you know will last despite making everyone involved miserable. You know that Park Shin-hye's character from Heirs is going to endure that marriage with grim determination and a hefty daily dose from the well-stocked wine cellar.

The OTP from last year's Jinxed at First will last but only because she got a lobotomy and there's nothing more romantic than mind-wiping your future bride into dreamy compliance.

I think though one of the best things to come out of Korea in recent years is the romance plotline where Happily Ever After is not the point. Will they be together 4EVA is not as important as them being together and happy now. It's a good change.

Our Beloved Summer.
Love is for Suckers.
Every single couple involving a robot or deity.
Oh My Ghostess.
Feels Good to Die.

Leads I'm pretty sure started dating when the end credits started to roll:

Secret Forest.💚
The Fiery Priest (Priests can date, right? 😆 IDK, but Honey and KNG's chemistry can't go to waste).💚
Law School. 💚

Well, dang. Seems like every OTP is not OTP at all. From all the responses, that is pretty much the entire kdramaland. Lol.

I have not seen the drama, but the mention of Weightlifting Fairy surprised me. I've only seen clips and memes, and thought they were so in love. That they will last.

Jae on & Eun O in lovestruck in the city.
They had chemistry & all but doesn't seem like they'd last long. They are more convincing as a summer fling couple than those in long term relationships.

The otp from love struck city ain’t gonna work, ever. There’s just too many issues and communications and inferiority complex to have a healthy healing relationship. So yeah, that’s definitely doomed.

Are You Human? : I don't see how a human can date a robot...
Matrimonial Chaos : Both couples were a big mess.
Beautiful Love, Wonderful Life : it didn't make sense that the big sister got back with her husband... (it was a bad family drama)
TKEM : they don't live in the same universe and he's a King...
Full House : I'm still trying to understand how they fell in love...

It looks like a good number of examples are when the writers made the leads such opposites or with such deep conflicts that their pairing seemed impossible until the last episode, and then the OTP was patched together with dollar-store glue. My most bitter disappointment in that category remains, Something in the Rain.

I'm surprised so many folks felt the OTP in Our Beloved Summer was unstable. Maybe I have to rewatch it. What did I miss?

The most obvious: the main couple from Nevertheless (main picture of this thread). He’ll try to be a good partner for a while, but in the end he’ll end up hurting her again and again. He’s toxic.

Runner up: main couple from Why Her ? I couldn’t believe in this couple at all. The age difference or rather difference in maturity is simply to big.

I actually disagree about Crash Landing on You. In my imagination, they do the Switzerland thing for a few years until Jeong-hyeok's father dies and Se-ri gets pregnant (these happen around the same time, don't question it). They communicate with each other through the foundation to arrange everything and then Jeong-hyeok's mom accompanies him to his next overseas symphony performance and they both defect. The mom gets to live in the same building as her son, daughter in law, and twin granddaughters, JH and SR get to be the cutest family ever, and JH just plays piano in the south instead. *ahem* Not that I've thought that much about this.

I don't have high hopes for the lead couple in Search WWW. The whole marriage thing doesn't have to be an insurmountable barrier (Because This is Our First Life couple managed to figure out how to make it work for them) but they already let it come between them once, and neither of them feels any differently at the end of the drama. I would have thought that marrying a guy with non-Korean parents would make a difference, since there are lots of traditions you wouldn't have to worry about that some women might take issue with. But they never even spent much time exploring why marriage was such an issue for her, so it's not clear what would have solved the disagreement, if anything.

Looking through my list, I much more often imagine a happy ending for couples that were not the main focus of the drama haha!

There’s only one couple that I can think of being together forever—that’s the Coffee Prince couple.

I'm a bit late to this post! Boyfriends/girlfriends with violent or volatile tempers in K-dramas will probably not last no matter how reformed they are after finding their OTP. Prison Playbook, It's OK Not To Be OK, My Liberation Notes and of course, Boys Over Flowers. In BOF you not only have a boyfriend with a violent temper you have the "soulmate" hanging around nearby. I don't see a good end to this relationship.

whenever there has been hitting, thats a no. and if you hit someone, you´re just a universal no. except self defence.
deliberately throwing on judo mat on purpose while knowing you might cause internal injuries, and then still dating
dont date whoever has a major drinking problem, but the korean nation would die out I guess.

but on the opposite side, why can´t you just date a zombie? besides the obvious fact they are already falling apart without having their heart broken?

I try to picture most of the couples in dramas lasting because otherwise, what's the point, but I totally don't see the couple in Do You Like Brahms? lasting long. Both are too self-effacing and passive, they won't actually say or go after what they want. It's one of the few dramas where I thought the leads were actually a bad match.