The report does not say she assaulted him. It attempts to provide a narration to explain why they were both so upset and the arguing had escalated to physical. He grabbed her face, so he was also physical with her, it was not a one-way physical fight. They had done this before, IMO. The way the cops wrote it up portrays her as irrational and more upset than the man in this situation, the POI who probably is responsible for her being missing. The cops wrote: "The male tried to create distance by telling Gabbie to go take a walk to calm down. she didn't want to be separated from the mate and began slapping him."
That's the hysterical woman part of the story and I doubt very much it actually happened that way. That sounds like the boyfriend's POV, to establish how "nuts" his girlfriend is. And police reports are not infallible.
Just IMO