OP, this is so important. Obviously, you get to make the final call since you own the house but that doesn't make your girlfriends feelings less valid.

My SO, our young daughter and I lived with his father for about a year to help him recover from heart surgery when his aorta ruptured and he almost died. He owned the house but we still helped with the bills and we did all the cleaning, cooking and grocery shopping. He would often be very rude and would always say "its my house I'll do whatever I want" whenever we confronted him about his behavior. The final straw was when he gave us a two day warning that a couple that he knew was going to be staying with us for three weeks over the holidays. They brought a pet tortoise and a vicious little dog with them. My SO, would had tried handling all of his father's previous unsavory behavior very calmly, was fucking pissed. Did we legally have a day? No. Of course not. Should his father at least taken our feelings into consideration? Yes. We had so many reasons to not want these people around. They were loud drunks. They were unemployed and obviously wouldn't be helping buy groceries. They had screwed over every relative they had to the point that they weren't even welcome at their Christmas parties because they stole their grandma's narcotics. All my SOs dad said was "it's my house. Leave if you want." We did. We had to wait a month before our house was move in ready and that month was hell.