Does she have a separate room? I guess she is a glorified tenant!She sounded more like a tenant than a partner!
I'd say she felt out of place last night cuz she knows she basically just moved herself in. She probably feels threatened that Wills friends will tell him that she's taken advantage of the whole situation and that it was too soon. She wont want him having contact with anyone that might make him see sense.
If Will breaks up with her, where does that leave her? She appears to have no family, no friends, no job (I suspect) and no home.