Ive literally seen that scenario play out at least 3 times in my life. All were during highschool and girls being catty with each other.The thing is, this manga would be so much more enjoyable if the characters actually acted like people. I mean, seriously. "Oh I bet it's so much more fun hanging out with them than it is with us. Grr, this ruined my mood. Let's leave our "friend" behind guys!" is such a fucking insane thing to drop just out of nowhere but NO ONE seems to register that as unreasonable as shit. And iirc (it's been a while) the previous chapters established this friend as at least caring of Hoshigasaki. So... why is she acting like a shitty caricature of the clingy bitchy girlfriend archetype???
There's only so much suspension of disbelief can do, man. And that doesn't just apply to, say, a fucking dragon appearing out of the sky. It also applies to how people act. I've been to high school, I've seen people. The more intimately real setting means that your writing must also stick closer to the norms that we know of. So... why do this? It just seems like a cheap and shitty way to force conflict when instead you could, say, centre the conflict around an ACTUAL conflict between the girls. Maybe friend A (forgot her name) has some past history with Nanamura or Hanamitsuji or something. Maybe they stole her bread or something. Idk. Just not... this.
The only real difference with irl is she didnt straight up call the other girl out like that. They were always more indorect and threw slight jabs at the girl like "oh guess you gonna go jave fun with THEM instead, OK side eye". Thy also started making space and avoiding the one they didn't like. Yes even the "my mood got ruined, lets go" happenee and then they started trash talking behind her back and spreading rumors.
Maybe you got blessed with a good school life or maybe my classmates were particularly shitty, idk which, but stuff like that does happen irl. Remember these are just highschool girls, they'll get petty and start drama for whatever dumb shit. Even dumb shit like "wow becky didn't come to hang out with us last 2 weekends, bet she was just talking shit about us to her new friends. What a bitch"