AITA for refusing to give my niece our dog's room?

NTA. OP had no obligation to let the niece stay in the first place. OP had no obligation to give up the room after the niece agreed about the couch and ambushed OP with her mom, complaining when she finally arrived.

People are arguing that OP is probably testy from sleeping on a couch for a month while her aunt sneers at her. If the niece really is smoking weed inside (let me be clear, I have no problem with weed), that's still disrespecting someone else's living space. You can't argue that she's being a good house guest if she's also partying and coming home late, potentially waking up other people who live there.

The niece is 24, not 18. There's no excuse for acting shitty and making comments about her cousin's engagement ring having been on your own for a while already. She's a full grown adult.

Lastly, it's not uncommon for people to give pets their own room. While OP could have been more accommodating, it sounds like she was hesitant to make this arrangement in the first place and is in no way obligated to change anything.

I lived with my aunt and uncle for about 6 months when I first moved out and went to university. I moved out part way through my second semester because they gave me a curfew and were acting too parental for my liking. I had cheap rent, all my meals were taken care of, but didn't have a lot of privacy. However, I knew what I was getting into when I moved in with someone else's family and I respected their space. If she doesn't like it, she's free to leave on her own volition.

/r/AmItheAsshole Thread