I don't want my brother's girlfriend included in everything. He's now taking her on a trip and did not invite me.
Why does she have to be invited to everything?
He thinks she's very much emotionally attached to him.
She's your brother's partner so there's nothing wrong in planning trips just for themselves. I understand you like your brother but you shouldn't be so possessive.
I hate people that are attached to my brother.
Your brother has his own life though since you are both adults. It is pretty normal to take trips like this with your partner and no one else. It may be hard to accept, but it is just part of being an adult.