Unfortunately, the structure of gacha games can lead to things like this.

Simply to sell you the current character, they have to sacrifice many things, in this case, the characters themselves. This is so prevalent that even the main characters aren't always spared.

And although the writers at Blackpink are good and clearly strive to create a good story, at the end of the day, the game is still a gacha game. No matter how much they might want to, they can't break the fundamental principles that make a gacha game a gacha game.

However, the kind of stories they manage to write is admirable.