Dad and girlfriend fighting because of me?

In my opinion, it doesn't sound like you were selfish. It sounds like the housekeeper is in charge of what she was doing and you did her a favor by saying that you would take over and she was free to eat or wash or whatever. I don't know anything more than what you've posted, but it sounds to me like your dad's girlfriend is the selfish one. Obviously, I wouldn't say that to her or to him because the last thing you want to do is purposefully come between their relationship. Maybe the next time they're arguing about you, you could go in and ask in a calm, non-argumentative manner, "What actions tonight made you feel that I was being selfish?" Try to understand why they say what they say. If they won't let you into their conversations, try to find some time to talk to your dad individually. Tell him that it hurts your feelings that you feel like his girlfriend doesn't like you and you don't think you were being selfish. And that if you were selfish, you're sorry. Maybe try to talk to him about why she doesn't like you. It seems like she may just be jealous that you come first in his life (which you should because you're his daughter and he chose to have you). She could be jealous of that role or she could just be jealous of anyone that takes your dad's attention away from her. No matter what the cause is, she may be completely unfair, and I don't think you should sit back and take it. I think if you can talk to your dad, that will be the best thing. I would recommend not attacking her: instead of saying "She...," I would say "I feel..." That takes the blame off of anyone and makes your dad pay attention to the emotions. Good luck! Just because she doesn't like you, doesn't mean there is anything wrong with you! It's important that you know that! If you're respectful to her, then she is the one with the problem.