AITA for refusing to let my girlfriend take a naked selfie in the bedroom I share with my 12yo niece?

I'm 23M and I've been dating my current girlfriend (23F) for a few months. She's great in every way and I've already mentioned to her how I think she's a lot like the person I'd like to be my wife. Most of our time together goes great. 5 months ago I moved into a new house, though, and it's started to become a problem. <br><br>Back in 2018 my dad died and then a year later my sister died in a car accident. She left behind a baby girl who was only a few months old. I'm the legal guardian and it was intended to be a temporary thing until my niece was older, but she's still only 12. I keep the door to my bedroom open when my niece is awake and I've tried to explain to my girlfriend that I'd rather we don't have sex in front of my niece and I definitely don't want her walking in on us naked or anything like that.<br><br>I've tried to explain to my girlfriend that I really don't want my niece walking in on her in the nude, but she seems to think this is a double standard. She keeps saying that she's fine with me walking around naked after a shower, and that a nude selfie isn't any different, but for some reason she always seems to want to take these selfies in the room I share with my niece. She even accused me of perving on her, because I don't want her taking nude pictures in "our bedroom". <br><br>I have tried explaining to her that the main thing is that I don't want my niece to walk in on her, but this just makes her defensive and she tells me she'd never do anything sexual to a kid, so she doesn't see the problem with taking nude pictures in the bedroom as long as my niece is asleep. She's offered to let me watch while she takes the pictures, but only if I'm naked too, and I just don't see what the big deal is if she takes her nude selfies in her own bedroom.Honestly I'm not even sure why this is such a big deal to her, because she isn't into posting nudes anyway; she only takes them for personal use.