If it is something like ‘I will be going for a walk after supper by myself’ and after supper you don’t go for the walk because something else came up, not only can you change your mind, I would recommend changing friends. They have no right to control your life
Now, if you say ‘I am going to sign up for ballet to meet girls’ and it has nothing to do with your friend but you are trying to influence him into signing up for ballet and you keep repeating it over and over, then yes, you would owe him an apology if he signs up for ballet and you are not there