<human>: Give me the gist of the text in a nutshell

So, last night I decided to sleep over at my girlfriends place because I have been having problems with bed bugs at my apartment (a real disaster and whole other story). My girlfriend has been renting a room in a house from a middle aged woman for the past 2 months. Anyways, I get there and we go to sleep. At around 7am I hear a noise that sounded like the door opened. So I roll over and look up to see this lady just standing in the room staring at us with the door now halfway shut. After many seconds of her just standing there she says, "Good morning". I just stare at her groggy and befuddled for a solid 8 seconds wondering what the hell is going on and why is this crazy lady standing in the room. I look over at my girlfriend, who is somehow still asleep, and I shake her to wake her up. The landlord then starts leaving. When she wakes up she is like, "Was someone just in here? WTF!".  Fully awake now, she flies out of bed, puts on a robe and heads downstairs upon which this conversation ensues:

GF: Were you just in my room?

Landlord: I thought you weren't home.

GF: Yeah, that doesn't matter. You can't just come in my room without my permission.

Landlord: I thought you weren't home.

GF: You NEED to ask for my permission before you come into my room.
Landlord: *leans in* Give me a hug.

GF: ugh *walks away*

So my question is this: When you are renting a room in a house from somebody, can they do this? I was under the impression that the room is solely yours since you are paying for it and that no one else has access without your permission (even the landlord). Maybe someone who knows something about typical rental agreements can shed some light on this.
<bot>: Sleep over at girlfriend's place. Landlord lets herself in a 7am thinking nobody was in there and that it's OK to come in as long as they're not there. Can someone shed some light on how rental agreements work?