I know what you mean. I told her that I'm a bit mad she would even ask or consider it. She just said "Okay I won't go."
I've told her that loads of times before with situation related to her ex.
Now I think she's mad at me because it's one of her favourite bands that she can't go see, it's Childish Gambino. I had a listen on youtube quick at a few songs, junk in my opinion.