Reckless: An It Girl Novel (It Girl #3) by Cecily von Ziegesar (I)

Jenny was totally enjoying the attention of the three hottest guys on campus. But she's ecstatic now that she's bagged arty Easy Walsh as her boyfriend. Unfortunately he used to belong to someone else...Jenny's roommate: gorgeous, popular Callie Vernon. It doesn't take long for Tinsley to use this to her advantage and soon the girls are split across enemy lines. But all's fair in love and war, and Tinsley better hope that the one secret she's managed to keep hidden for years doesn't get revealed... Who knew boarding school could be this good?