My (27M) girlfriend didn’t come with me to a funereal (27F) when I asked her

My (27M) friend’s mother died and I asked my girlfriend (27F) to come to the funereal with me the following day. She told me that she had an nails appointment at the same time that she couldn’t cancel last minute and that she would come if that wasn’t the case. All of my other friends girlfriends were there and she wasn’t. When I confronted her about it she told me that she sees this friend 3 times a year, she doesn’t feel like he is that close to fo out of the way to attend his mother’s (who she has never met) funeral. She said that she would have definitely canceled the appointment if it was for any of my other closer friends and that she would have come anyway if she wasn’t busy. I am still mad about it and we had a big argument but I feel like she doesn’t understand me. The thing is that my f friends and me would do some things out of principle, but I feel like she is not that type of person. Is this very disrespect from her side?