Ok so they were rude trail partners.  If all the trail riders are not on the same page they should have told you they wanted to break away and done it in a controlled safe place were all riders could be prepared.  I would not ride with these people again.  If some of the riders wanted a different ride they should have just stated they wanted to break away and ride on.  To trot off with no warning is dangerous and not very considerate of all the riders.  You are correct in working your horse to be sure that this situation will not happen again with your horse.  Happy riding.

I think it should go without saying that we look out for each other on the trail . These riders were not doing this.  Yes, everyone's horse should be perfectly behaved on the trail, and we should plan with our companions at the start of each ride what we will and will not do. But on my planet things don't always go that way ! Bottom line, these riders chose their fun over your safety, and I would not want them as trail buddies .