I'm not going to let my boyfriend take a trip with his female friends.
Is there some reason behind it?
Because I don't want him to be with other women.
It is natural to feel uncomfortable about the situation, but trust is major in a relationship and you should trust him not to do anything stupid with his friends. Don't try to control him.
He has done many stupid things in the past and this could be another one.
He has to make his own choices in life and you attempting to micromanage what he can and cannot do is a recipe for disaster. You are risking him leaving you if you continue to be controlling.