The other day, there was a movie I wanted to see. I invited a friend to go with me, but they decided they didn't want to come because they were going with another friend. 
That really sucks... did you tell them how that made you feel? 
No...I guess I should have. I guess I really think they should have went with me too, or invited me to go with them. 
I would tell them.. and if it happens a 2nd time then they arent very good friends to have! :/