Boundaries, Camila always had them. Maybe that's why David saw her as uptight. Carefree, Lauren always let loose and had fun, lived in the moment.
Camila and Lauren grew up in the same neighborhood. They were used to seeing each other at family dinners and whatnot, sharing almost all of the same advanced placement classes, but they never really spoke. Of course, thanks to social media and school gossip, they thought they knew enough about each other to guess that they wouldn't make great friends in the long run.
Camila gets dumped by David, so she figures that the only way to make him jealous would be by breaking all her boundaries with someone he despises, and who else better than carefree Lauren Jauregui to fill the job?