It Only Hurts at First by Allison Rogers

Alice Matthews used to be one of those girls. Pretty, popular, perfect. Now, she’s that girl. Armed with oversized sweatshirts to cover the scars on her wrists, Alice has two objectives in high school. First, avoid Scott Henderson at all costs. Second, avoid everyone else.
By now, Scott’s unwanted advances shouldn’t come as a surprise. But when he steps up his harassment in gym class, the last person Alice expects to intervene is the school’s social pariah, Hunter Thomas.
Hunter doesn’t care about much. Not his classmates. Not the vacant seats at his lunch table. And certainly not his golden boy stepbrother, Scott. Alice Matthews, on the other hand, is an entirely different story.
Drawn together, Alice and Hunter find fragile solace in each other. But despite their affinity, Alice worries that their growing feelings will lead nowhere good. Not when Hunter lives down the hall from the one person she has sworn to avoid, someone who could easily reveal everything she’s been trying to hide.