AITA | Annoyed with my friend for ditching party for girlfriend.

Today is my younger brothers 16th birthday and I have spent the last month trying to put together a blowout birthday party for him. He doesn't have a long list of friends as we were homeschooled for a lot of years, so I reached out to all my closest friends to see if any would come to his party.

My closest friend of 5 years, someone I grew as a person with, told me early this month he would try to make it, and is now telling me the day of that his girlfriend has... cheer practice, and said quote "I dont go nowhere without her."

I was really counting on him cause I dont have many people myself to reach out to to begin with, and most people said they couldn't make it. Got a bit angry with him and told him he wouldnt have done this when we were younger. Screenshot of the texts are in my last reddit post if you want to see.

TL;DR - friend has attachment issues