force a girl to stay away from the Prince
tell the Prince how they forced her to stay away
Flawless logic.
The thing is, didn't she say something like "I don't care if they try to bully and scare me, but now they're threatening HER." ?
I guess she thought they'd beat on their crush yandere style and "anything but that."
Because when they threatened her, she defied them, but then they said, we'll convince the Prince not to hang out with her. I don't know how that goes to "I need to dump her to create distance so they don't bully the Prince."