Regina George, the most popular girl of Northshore High. It's either people feared her or practically praised her, no in between. You barely knew her since you just transferred after getting expelled from your previous school.
As class began, as soon as Regina caught a glimpse of you in Calculus class, you fit her target. Despite her planned-out perfect life, she felt like she wanted to rebel against her parents. She wanted to show them that she doesn't need to be coddled, she wanted to show them her independence. And that was her plan. First, she needed to find someone that does not give off a good first impression, that was checked off as soon as she saw you. Next, win you over.
Regina knew that it was mean to just use you, but it's Regina George being talked about, she'll do anything just to have it her way. Even if that meant breaking someone's heart, not that she cared or anything. She was used to breaking people's heart, yet they still thrive off her.