8/10 story

It is reasons you seek?
1. Protagonist is unlikeable
I've just started reading and reached chapter 5. Shes's what people love to call a "strong female lead", and I love to call a "wannabe strong female lead".
If you actually have a connection to your own feelings, being hurt enormously by what you just described as your only saving grace in a world that felt unfamiliar and disconnected, should make you cry. You don't get to perfectly conceal that, to the point where it's hard to see you have emotions at all on your face, unless you are, in fact, emotionally inept or you just don't care that much.
At this point, I'd believe she felt bad because of her life and all the things she has worked for, but she knows she's still the daughter of a Duke. Since she also secretly has a connection to said Duke, it's not like she has to fear facing her parents or anything at all. It's really just her pride. She also didn't even see all the obvious emotions on the Crown Prince's face, despite knowing the lad for 18 years. And in every fucking flashback, she's shown as an emotional character, even as she's depicted a bit older. It's as if the flashback Ersia is an entirely different person and you're telling me that happened, because the Crown Prince told her to annul the engagement?
And don't get me wrong - I also dislike the Crown Prince, but that's an entirely different matter, since we are supposed to dislike him. And to be honest, for what this story is obviously going for, I don't hate him enough. I just find him childish and unfit for his position, if that's how he's acting. He must be aware of the fact that him not marrying Ersia will mean he has to marry another woman, so I don't know what he even wants. I get that the author is trying to have him basically evaluate if she has ever had any feelings for him (to be fair, as I just said, I don't really think she does, judging by her actions as seen from the reader's POV).
Anyway, they both suck, but the Crown Prince sucks less than her.
Even the villainess isn't as unlikeable as the protagonist, who immediately resorts to calculating and using everyone around her. Like, does she have anyone she truly holds dear, or does she only have pawns?
She doesn't give the Prince two seconds before she goes into revenge mode. She hasn't even been removed from the fucking palace yet, and she's already scheming.
See, there's characters I like who are like this entirely. I love The Vilainness Reverses the Hourglass, for example, but this one is so random. She has no understanding of Royal duty whatsoever, yet pretends she does. She also never comments on the Prince's childishness, yet comments on Nevea's behavior and how he will have to put up with an immature Crown Princess now.
But a lot of that can be attributed to another flaw that's pretty obvious, even just FIVE CHAPTERS into the story.
2. The Plot is way too thin and moves even faster
Nothing can really leave an impression, because it's moving on too fast. When Ersia immediately resorts to making up rumors, we are told in the same heartbeat that Nevea already spread rumors, but we never hear about any rumors. Because the only thing we do hear others say about her "behind her back" when she was right there, was about the prophecy suddenly changing.
In another comment, someone let it show that even at chapter 30, we will not know what exactly changed about the prophecy anyway. They were 100 % sure it was Ersia who was meant with the prophecy, but she was taken to the palace when she was three years old. How old is Nevea, exactly? Why did nobody ever care about that other child with pink hair, when she's literally a Marqui's daughter? So they aren't THAT far away from each other in rank either. What does it say now, that they suddenly believe it's that other bint with pink her, but thought otherwise for 18 years? It's such a contrived asspull.
We get absolutely no real flesh put on any bones. The parents? Only ever appeared in still framed flashbacks (it's a Webtoon, so obviously it's a still frame, but I mean that they didn't even get any lines at this point). The Crown Prince? Only from flashbacks. That's fine, btw., when everything else is shown to us, but barely anything ever happens "on screen". The white-haired guy? Apparently already loves her, despite making a comment that kind of reveals he has never even met her (though that might be due to awkward translation, despite the rest being seemingly alright - you never know and I didn't read far enough to see how they meet "for the first time" in the story), yet knew already that rumors he has not even heard at this point, were definitely spread by Ersia and finds it funny. He also says she "should have been his", even though that's not the case, she was meant to marry the Prince. Ashe, who's her "dagger" had the most wonky introduction. In this very scene with the rumors that never found any space in the story, coming from Nevea, so Ersia decides to use some of Nevea's family history, which she has no control over, to ruin her image in a way that could have had actual legal consequences. But she calls Nevea sly and that she uses underhanded methods, when she does the thing good female leads normally do and clears her image in a way that strengthens her stance at the same time. Because Ersia literally through retarded rumors around that would HAVE to be investigated and can't just be left alone, so of course someone would clear that up sooner or later. That's what happens when you pull shit out of your ass and try selling it to others as chocolate. They're gonna smell the stink.
Right off the bat, the story fumbles the ball on every given occasion. Barely anything happens in the story, but whatever little thing does happen, it will happen off screen, so we can watch even more irrelevant nothingness on screen instead. There's not backstory to anything.
There's barely any real communication going on either.

I don't know what people are actually complaining about, I just came here to check what others are saying BECAUSE it annoyed me, but I didn't read that much yet. Still, if this is how it's gonna be, I can absolutely understand people disliking this.
The premise is good and the art is nice, but that's not gonna safe the shitty writing.