My[27M] GF[26F] chose to go to her dog's graduation over my promotion dinner

I'm in a state of confusion right now and need help to gather my thoughts.

My GF and I have been together for 2 years. She also has a 6 year old pit bull whom she really loves. I've never met her without her dog. She loves taking it with us on dates and we've always accommodated around the dog. She has openly said things like her dog was the most important thing in her life. I get it because the dog is like a child to her.

Last night was my promotion dinner. It was a dinner catered to me and a few employees who recently got promoted and it was a pretty big thing for me. My boss even gave a toast in my name. I really wanted her to come and I told her a month in advance to which she agreed. But last week she found out her dog was graduating from some sort of training and they were having a dinner with the other dog owners like some sort of graduation. She told me she couldn't make it. I pleaded her to come because I had already told my boss my GF would come but she didn't. I had to make up some crappy excuse and it kind of felt lonely.

I know she loves her dog but I think she may love her dog more than me. Do I break up with her?

TL;DR GF chose her dog over me