
I liked it in spite of everything. I'd love to see it as a film done in the same fragmentary, out-of-chronological-sequence style :).

Yep, I like it to. In a way it reminds me of "The Assassination Of Gianni Versace: American Crime Story" (not sure how well known this programme is or if others in this series follow a similar jumbled timeline theme, but it was available on the BBC). Having a muddled timeline, where the pieces eventually all come together is something a bit different to the usual linear offerings.

Taesoo should move out so they can have some space and not constantly deal with each other all the time. They keep setting off each other's insecurities and I'm not enjoying it lol.
I mean, there's awkward and there's acting-like-an-alien-new-to-the-dating-concept awkward. At least she's a million times nicer than his ex so he'll wait this out...

This is the best take on an age gap, rich old/young college kid BL story I've ever read. Ji Hye-Kyung understands how power dynamics influences human behaviour. Kim Sihoon can't help but step past boundaries and take charge of certain aspects of Junyong's life, because he cares and because he can. But when you do that once, you'll do it again, even in small ways that can be rude and off-putting. And rather than encourage Junyoung to have some financial independence he prefers him to be more dependent because he's not sure wtf he's doing but he wants to have Junyoung around long enough for him to figure it out.
For JY this is all thrilling yet destabalising at the same time. He does feel small and humiliated, but at the same time heady and infatuated. His position feels incredibly insecure esp and that whole Mari misunderstanding does not help. That is the only fly in the honey for me--I want it sorted quickly because I think the story has plenty enough conflict on its own without this weird "Oppa" farce.

If there was a scene in a shojo/josei manga in which the man told the woman that he only used her for sex, no one would be questioning his sexual orientation. We would all (rightly) view him as a manipulative, selfish hetero man and leave it at that.
Yet once it involves two men it's very easy for some of us to allow a question to remain and buy into Yuuya's argument. You know, Yuuya the homophobic, manipulative ass. Why?
Heterosexuality is not the default, y'all.

I buy into it because having sex does not define your sexual preference - that is still up to you. Experimentation is okay. More commonly it is pretending to be hetero - like in the josei scenario, if the guy said he was using the girl for sex but was actually gay, I would believe that he was actually gay.
Gay, strait or bi, Yuuya is still a manipulative, selfish jerk.

Let's not get it twisted--sexual activity does help to define one's sexual preference. One doesn't have to be sexually active to first define it, but one's sexual desire--or its absence--*is* a factor. (It's called *sexual* orientation, hello. Words mean things.)
This manga has shown no evidence that he's had any sexual or emotional interest in women for us to know that he's "actually straight". There are no scenes of him with women or any relevant internal monologue. There is nothing in the manga to show he was merely "experimenting". In his own words, he and Yura had an active sex life--enough that Yura assumed that they were in a relationship.
What the manga has shown is that he is homophobic, manipulative, selfish and deceptive--basically what he *says* cannot be trusted. You are right--it *is* more common for a gay person to pretend to be heterosexual than vice versa. So in the face of what we *know* is more common, and the manga at pains to present how into Yura this guy was (and obviously still is), at the drop of hat, you're willing to buy his "I'm really straight, stupid homo" story?
Oooookay. Yeah. Heterosexuality is not the default, y'all.

I'll be honest; a little bit of believing this fictional character is wanting people to accept me when I say I am bi instead of making judgments on if I am strait or gay based on who I am dating.
Homosexuality is not the default, but sexuality is not a binary. If this guy wants to define strait to include gay sex if you're not looking them in the face, than that is fine with me. He's probably a 1, 1.5 on the Kinsey scale if we go on what he says, because we otherwise don't know much about him. We don't know much about Yuuya because it's not his story. Nobody wants his story because he is an ass.
He's the type of guy who when meeting his ex after five years a) outs them as being gay b) shames them for not that he saw them only as a booty call, and c) tells them did them from behind because he couldn't cum when looking at their face. He also broke up with the MC by saying the MC was too needy instead of saying honestly that he (Yuuya) was only in it for the sex.
Regardless of Yuuya's sexuality, he was engaging in gay sex. That at least is something we can agree on.

"Sexuality is not a binary"
Never said it was. My argument springs from the central point that Yuuya is an unreliable narrator not that it's impossible to identify as a heterosexual just because one was once involved in a homosexual relationship.
Beyond that...
"If this guy wants to define strait to include gay sex if you're not looking them in the face ...."
is an indication of a problem. Again, I examine Yuuya's action within the context of the story in which Yuuya's relationship with his ex was emotionally abusive *at best*. It wasn't two adults on the same page engaging in fun sex play. Sexuality may be a spectrum but I'm not prepared to accept definitions that rely on whether or not one looks at a partner's face during sex. I don't see how that leads to anything but bi-erasure in a genre already known for the problematic Gay For You trope (popularised by cishet women).

I feel a lot better knowing the artist created this story with the intention of it ending in a break up lol. I know we're used to all kinds of messed up scenarios in BL but there is no way a college kid should stick with a relationship in which the other partner used to be obsessed with their parent and acts like a jealous teen (at 50+ years old).
When I saw him on the balcony trying to call Yoo Il I was amused but angry. Really, Ahjussi? Are you going to pull the "I'll Commit Suicide if You Reject Me Forever" card from your How to Become an Abusive Partner starter pack?
Issa NO. Get a cat. Start from there. (Maybe end there? Nothing wrong with being single. Take a trip, go to some gay friendly destination, relax, get your mind right.)
One of the most annoying things in the world is a sex friend who agreed to sex friend terms and then thoughtlessly decides on their own to push for more. *Annoying*. LOL I'm super biased against whatshisface for that reason.
Well that's what being human is. People who can control their emotions and not act selfish are very rare indeed.
It's not about expecting anyone to control their emotions--it's expecting them to be somewhat considerate which is well within the range of "what being human is".
I may not be able to avoid jealous feelings but I can refrain from interfering with the other person's relationships. If I find myself making that mistake I take a step back and reflect rather than push heedlessly along. If I can't do that then I show exactly why I don't deserve to expect more from the relationship.