What can I say? Your opinion is legion, I agree with all your points and questions. I seriously hope Seju is not thrown under the bus yet again, making her guilty for stuff she didn't have any participation in. Glad Seju is happy with Won, even if I didn't like the way One was executed.
Also, from way before in the main story I could already see Sumin was the main culprit for all her own problems and basically a super selfish and spoiled person. In contrast, Seju's only problem was that she had FEAR of abandonment, and that made her act in bad ways as a reaction to fears of losing Sumin (the initial cheating, sticking around, etc).
I don't think Seju would participate in this side story, probably she will just be mentioned or show up a little for the last time right before it ends. I'm also happy that Won is there to help Seju move on from the long term haunting past, and that she actually has her own complicating background even though it didn't get exposed in depth rather than a white paper like Sungji. Currently I just hope the author could at least try to develop her character more but it looks like Sungji can't stand a chapter without Sumin so yeah, perhaps next chapters will just focus on fluffy moments of Sumin and Sungji and how she cheered her up.
Hell, you said pretty much what most readers out there are probably thinking about this last side story, which honestly has been a letdown in terms of storytelling so far.
The evidence is piling up to prove that Sumin has always been an asshole, even before the shitstorm that happened with Seju cheating on her and Seju's brother assaulting her. If you're not her lover, she tends to treat you like crap or maybe not spare a single thought about you. Even if you're her lover, she has a habit of being dishonest with you, lying and taking you for granted - basically a doormat. Nothing really has changed much about Sumin's personality from the main story, and here in this last side story.
And as expected, it seems like Sungji has stepped in and played therapist for her again, magically helping her forget all about Sunhwa just like that. It saddens me the author is sending the wrong kind of message, meaning you can be an asshole of a person but so long as you have an angelic partner with you, there's no need for you to learn from your mistakes in the past and improve yourself.
To be fair though, maybe the author is just showing that women like Sumin exist, and they do plenty. Usually, main characters are good people, or at least turn into good people by the end of the story. But that's just fiction xD Most people never change, and a lot of times the people we at first glance consider to be "mean" (like Seju) are actually being led on/manipulated by the Sumin type of person.
In other words: Sumin is "covert", she is passive, shies away from responsibility for her actions, self-centered, she lies by omission to get what she needs and to get away from any feelings of guilt. This is very different from what most people identify as a "villain", because it's not obvious, it's not in your face. And it's very easy to be fooled by this kind of person because they seem like a victim to whom bad things are always happening, and if you get on their wrong side, you will be made to seem like the bad person who victimized them too (Seju). That's why Sungji sticks around, and that's why Seju stuck around out of guilt. It's a mistake that happens a lot.
So...what have happened to the author's writing? Does she even realize there are too many plot holes in just the 2 latest chapters? I just feel like the more she writes, the more mistakes can be found. My expectation for all sidestories at first was pretty high yet because of a dozen of random, unnecessary scenes in Paradise that lessen the story's coherence + the rushed ending of One with many things left untold that I gotta admit her writing is quite bad (then I reassured myself that was a bit okay for a side story after all) but I've never thought it could be this bad until I read chap 126. So, the ugly truth could make people feel irritated, but I still want to say it:
1. Couldn’t she come up with a better reason on why Sunhwa died? What kind of work did she experience to have her health deteriorate? How much money did they need? Don’t her parents have savings? Why her parents still managed to live through bankruptcy thought they were the core problems but their daughter got to pass away?
2. She twisted Sumin's character, or this was really the sort of person she is - Sumin's true color? I’m not sure. But all I can see now is a selfish, entitled Sung Sumin who always tries to make excuses for every mistake she made. Sumin wasn't that drunk based on the unopened wine bottles but how could she just toss aside the contact note Sunhwa gave to her like that? Even if she forgot about the unfortunate meeting with Sunhwa the next day, and she had forgotten every single detail of it for more than 10 years, but just look at how fast she remembered it when Nammi asked her to recollect memories. Lmao. And the author was even caught off guard that Sumin's behaviour in newest chapters was criticized in Kakao's comment section that she tweeted something about it, thinking that all Sumin did to the best friend who used to like her were acceptable?
3. The point mentioned above led me to wonder: Don’t tell me Alggumba’s planning to shift the blame on Seju by having Nammi saying “I just know you two were close until you met Baek Seju…” – UGGH, ex-excuse me? Just like the dark pink haired girl who slapped Sumin in this chapter. It was actually Sumin who have problems, Sumin herself is the problem. I once thought it was Seju who had turned Sumin into a distant person to her friends. But no, it was Sumin who was willing to make all the choices to stay far from her friends, even when Seju said she didn’t have to. It was her who chose to confront her darkest moments when she lost both of her parents and first love by hooking up with every woman in Korea. Nobody owes her anything.
4. People seemed to sympathize with Sumin's claim "Because you liked me that you couldn't be friends with me" that they don't even know how ridiculous it may sound to Sunhwa when she just asked her "Why should I go back to you?" and Sumin: "Because you liked me" - What is this hella disgusting reasoning? Because I used to like you that I should run into your arms and have you bang me after all these years you shut me out of your world? Don't make me laugh!
5. All Sumin cares for is basically about whether or not she would lose face to her friends, to Sunhwa, or even to herself. As long as nobody makes she feel embarrassed, she will be quite okay with it. At first I didn't want to to believe in this point, but her self-defensed act after the reunion to Nammi by saying "How ridiculous it may sound to the others - do you enjoy making me look stupid that much?" and "in any case, it might have been a good thing that I didn't run into Sunhwa after that" --- Did she even care for the fact that Sunhwa was dead, for the sake of her constant struggle to make ends meet? Sumin was scared she might have lost her face to Sunhwa in the second encounter? But did she ever think that if she ran into her after that, they could just sit in the same table, talking things out in a sober state, and she could have helped Sunhwa to overcome her hardships a bit? So that Sunhwa wouldn't have died for this lame reason? Sumin is rich though?
6. Why the letter was obviously placed on the table? As Sunhwa just died a few years ago and Nammi said Sumin wasn't in a state to hear more bad news, I would assume that it was during the time Sumin broke up with Sungji, and Seju already said farewell to her before leaving to Jeju island - which means at the end of 2015 - in around November exactly 4 years ago. And Sumin and Sunhwa met again after her breakup with first love Seju - which also means in 2005. So Sunhwa really kept that letter for almost 10 years until her death? After knowing her crush becoming this ugly? I can understand as to why Seju lingered on Sumin for 10 years, they were staying beside each other physically and mentally, and they still have feelings for one another. But Sunhwa...Ugh, she couldn't even say a single word to Sumin. Couldn't she meet new people during those years? Yet still kept the letter? I'm sorry, I. don't. buy. that. Don't try to make reasons on why she left it at that place. It's just that Alggumba couldn't think of another faster way to make Sumin know about Sunhwa's untold confession in details. The same way as Seju reading her mother's diary. But the diary was a bit more convinced to me considering Chahee was living in the villa all alone, which bored her to death, and at least Chahee didn't leave the diary right under Seju's bed.
7. Where is Sungji? Isn't this side story is meant for Sumin and Sungji 3 years later? Why is too much of Sunhwa in here, with this kind of approach? Why was she in Paradise when eventually all she could have is her death? Couldn't the author try to show Seju's school life or one of her arguments with her siblings/step-mother? Couldn't she try to develop Sungji's character more instead of letting her be Sumin's therapist all the time? Is she just there as an angel to heal Sumin's past wounds? Why was the story focusing too much on recycling Sumin's drama, which all people already know and get tired of?
8. Last point, I don't know this Sumin. Either a too hella selfish, entitled Sumin or a freaking soft who always smiles shyly to her friends that the author is trying hard to show. She seems very unfamiliar to me now. Am I reading a different story?