There's only so much I can do for you
After all of the things you put me through
Oh, I'm lifting you up, I'm letting you down
I'm dancing 'til dawn, I'm fooling around
I'm not giving up, I'm making your love
This city's made us crazy and we must get out
-Must Get Out, Maroon 5
While the other four members of the Breakfast Club were having their lunchtime escapades, Claire had spent lunch in the cafeteria with her girlfriends. Her lunch period hadn't been as emotionally taxing as the other Club members. But it had been, as she would say, a total drag. Annabelle was completely silent and lost in daydreams the whole time, Erica was giving Claire dirty looks when she wasn't asking her suspicious questions about guys and her summer, and Charlotte wouldn't shut up about Andrew and what she was going to wear tomorrow to impress him. It had been all she could do not roll her eyes every second of lunch.
But it had made her decide that the Breakfast Club definitely needed to get together that afternoon.
She had to do something to get Allison and Andy back together before Charlotte got her claws into him. it wasn't that she didn't like her friend anymore, or that Charlotte was necessarily always a bad person. In fact, she was a decent, funny, strong person—whenever she wasn't around Erica. Erica was the real problem. She was sharp, conceited, mean, challenging, and strong and authoritative. She and Claire were friends, but they often clashed. The only reason they became friends was because they were expected to be; their parents were friends and they ran in the same circles with the other popular kids. Erica needed popular girls on her side and in her group, making her look good; and Claire knew it was better to be on Erica's good side than to risk getting on her bad one, and facing her wrath.
She was the only girl in school more popular than Claire, and everyone but Claire wanted to be her. But no one more than Charlotte. Charlotte was basically an Erica clone. She did everything Erica did, believed everything she said, and when Claire cried about pressure to Brian in detention, she knew there was no one who felt the pressure more than Charlotte did. She had even been dyeing her hair blonde like Erica's for as long as Claire could remember.
She had to keep Charlotte from worming her way into coupledom with Andy. She just had to. And not just because Allison was a friend that she truly cared about. But because she cared about Andy, too. And as much as she liked Charlotte when she wasn't acting more like Erica than her actual self, as long as Charlotte was under Erica's thumb she wouldn't wish that on Andy. Besides, Andy was the one who kept her strong, in the times when she came close to being a total bitch and giving in to pressure. She knew if Andy hooked up with one of the girls in her group, he'd go rightly and deeply into stereotypical jock mode and there was no telling how lost she would be without him. She had to somehow stop him; help him get back together with the girl he really cared about.
(One could only imagine if her caring about Andy would have been so much the case if she knew about the secret and rumors Andy knew about her but didn't do anything about.)