Help finding story. Chad sleeps with guys roommate as he spies on them

Characters:
Main guy – Told from his perspective. Sleeps with easy roomate. Not sure if bf or just likes the gf/his crush.

Gf – last hook up. Wholesome and proper. Liked by main guy.

Roomates – at least 2 maybe more. First one is easy and hooks up with bf and then chad.

Chad/alpha – physically superior. Looks and size.

First, bf hooks up with easy roomate and then she later hooks up with chad after the first party/meet up.

Guy spies on them outside a window through the blinds and learns she was faking it with him as she is seen and heard screaming. Remembers no screams when he penetrated her.

Next party, every girl is vying for chads attention including easy girl and his crush. Guy tries to hookup with easy girl but shes distant and focused on chad. Chad leaves with another roomate leaving her saddened and unresponsive to bf advances.

Eventually beds gf(?).