As for the second part, Unknown doesn't really work in this situation since Op and his S/O knew the male at the door. Which from what I could gather, was the only reason the girlfriend opened the door in the first place. Because she knew who was knocking
They also both knew he had a history of being physically violent. A person showing up at your door at 2:30am with a history of drug use and being physically violent is reason enough to feel threatened.