I don't mind the working hard part, but I do mind being let down. I'm disappointed more than anything else. If you make a promise, a commitment to something then you should see it through and if by some unlucky chance you're not going to be able to make it, it's a courtesy to let people know.
Still, it's partly my own fault. Knew this was going to happen, if I'm honest so I do what I have to do.
Just very... annoying.