My mum and I are part of the same community club/hobby group. We are both adults. There was a social event happening tonight, which we both went to. When there my mum met up and sat with her friends. I had invited a friend who is not usually part of the club but who I know from elsewhere. Friend and I arrived together, and sat together, in a different part of the room to my mum.
On the way home after the event my mum told me that it would have been nice if I had told her beforehand I was bringing a friend. She said that her friends were asking her, "oh did Hannah (*not my name) bring a friend?" and "who's Hannah's friend?". My mum told me that she just told her friends she didn't know who the other person was because "why should she cover for me?"
I responded that if they had wanted to know who my friend was, they could have asked me. I don't really understand why she thinks "covering" for me could have been necessary - I don't see what there was to cover.
My mum was quite angry that I hadn't told her I had invited a new friend along. She seemed to think it reflected badly on her that she didn't know when her friends asked, and seemed to interpret it as a slight against her. For context I find my mum quite hard to deal with at times and I deliberately didn't mention that I was bringing a friend along because I am an adult and I am entitled (and need!) to create a little space between myself and my mum. I understand that, had my mum and I had a better relationship, mentioning that a friend was coming with me tonight might have been something I'd willingly want to share with her. But I don't think it was inherently wrong not to tell her. AIBU?