This is by H28 on onedirectionfanfiction.com it's wonderful and I hope you like it as much as me. Recommended for 17+

Jess has a problem and his name is Harry Styles. Harry is Easton University's resident bad boy, complete with hair down to his shoulders and arms full of tattoos. After a chance meeting at the semester kickoff party involving a spilled beer and a white dress, he suddenly seems to be popping up everywhere with that cocky little smirk on his face. Despite his presence seemingly surrounding her between sharing a math class, working across the street from each other, and his weekly hookups with her dorm neighbor Ashlyn; Jess is determined to not let him get under her skin. That is, until the heating in her building goes out and she's forced to spend the next two weeks living with the enemy.