AIT My [24m] boyfriend went on trip without me [22f]

My boyfriend was planning this trip with hist friend for really long time. They're staying at their friends house. At first i didn't think a lot about it. It wouldn't be a first time they do something similar. Turn's out, it's not only his friends that are going, but every each of them is taking their gf, when i raised the question about it he said that there is not enough space for me. I got invited to go day before trip, because their friend gave up. Of course at that point i couldn't go or would even feel invited to go. I feel really bad about this whole thing, both hurt and angry. We have really healthy relationship, he is usually very thoughtful and caring. I don't know how to approach this thing, I want to communicate it and let him know that i am hurted. I could never understand how for everyone's else gf there was a place in car and in home they're staying but for me there is not. I'm constantly repeating this story in my head and every time im more and more disappointed.