PLOT: young adult thriller

Our MC, a popular high school girl, starts to receive text/emails that she's being watched. At first, she just thinks its a joke but then the messages start to get worse until finally something happens to her friend/boyfriend before she starts taking them seriously.

Ryan, an average joe kind of guy, has had a crush on MC since middle school but she hardly knows he's alive. He notices something is wrong and after finding out someone is out to get her, he uses his tech knowledge to hack into her system without her knowing to try & help her.