because they are being controlled/brainwashed to hate the MC, they don't know why they acting cruel towards the MC, so when they relized it they regret it and don't know how to apologise because they also don't understand why they acting like that (it's the system)

basically it's about the aftermath of a system story. What happened to the replaced son when a system-clad daughter arrives.

No, the girl was not good in so many ways, she basically agreed to the system so she could snatch the happiness away from a perfectly normal (def. Rich) and happy family.

The novel mainly shows how everyone affected by the system woke up and finally realized that they have lost what's truly precious and did something completely irreparable.

Hate:

No explanation how ML just suddenly fell in love with MC when he is still thinking about his "Little Mermaid"

Why the people around the villain (esp the Brother and Father) did not dig deeper as to how they could get manipulated so easily, so much and so loong. Just passed everything as "what's done was done, no excuse" and remaining silent instead of apologizing profusely and sincerely that it seemed like they were puppets being controlled those times and can't think basic logic (like doing a DNA test).

The way the plot was divided. The later part of the story was a bit boring and I had to stop at 139

A lot of the chapters past chapter 80 get filled up with talk about the MC's work and while it's not bad, it does certainly feel like it's just. There. And it probably is just there as a plot device. I think the first two introduced (the animated show he created and the movie for his father) were fine and fit well into the plot, everything else after just wasn't that interesting unfortunately. I think largely because they lacked personal connection to the plot/characters.

The MC's father and brother. Not going to lie, I'm hella biased for familial relationships and such. When I read the summary, I was expecting some reconciliation or even a distant "I will not forgive you immediately, but I still want you (distantly) in my life".

The story does not immediately go in that direction, which is understandable given the absolute abuse MC went through from his family. He was essentially the beloved pampered son and brother and then woke up to being treated like the spawn of satan just because a chick showed up on his front door, was crippled by his own father, and had some really REALLY bad insults hurled towards his person. I am not surprised by his attitude near the end.

However, I'm just sitting here looking at my screen like "Okay, but that wasn't their fault though, that's the system's, what the hell???" They, along with basically the entire world but MC and ML, were essentially brainwashed into giving all the love/common sense they had to the random chick #6 from hotel 69. It probably wouldn't be so bad if every other 1-2 chapters, there wasn't a cutaway to the family feeling sorry for themselves in time out while looking pitifully at MC+ML having fun in a kiddie pool. It happened a LOT. At some point, it just got repetitive.

I admit I highly sympathize with MC's family purely because??? They just?? Got brainwashed??? They don't even understand what the hell happened themselves. They, and many others, literally had their lives/relationships ruined by random chick and for some reason, the author though constantly showing their pity party while taunting us with how they'll never get it back.

The fact that the world exists in a novel is not really explored beyond the narration/translator notes or, later on, when the system actually comes back to pretty much torture random chick #6. While it does get noted occasionally how odd that the random chick seems to have had a FL halo around her, nothing beyond that was done about it. Which makes things feel... a bit incomplete? Like there's a collective haze that literally the world had been under for 2-3 years, but now that it's gone... no one??? is??? a bit confused on what the f*ck happened???? Or even makes a comment about it beyond just thinking to themselves "I'd look crazy if I told people that I was under mind control for 2 years" as if half the sh*t some of these characters have said or did wasn't already crazy.

The author also repeatedly shoots the thought of confronting this truth down, but it feels like they just didn't want to write a deeper story much further than what they already were doing with their commentary on plagiarism. I definitely understand not wanting too many things to muddle that, but it feels like it got muddled in the end anyway because of the story dragging on.

spare for the "evil" little sister, who seemed to bewitch/enchant/drug/voodoo the people around her which caused them to 'lose' their minds, she's a clear villainess, in which I also somehow see her as one of those who were also controlled by that unseen thing which caused her to act Mary Sue-ish with heart and mind as black as a bottom of a pot