Sometimes people make promises just to make you happy..
When the time comes for them to do what they said they would, they expect you to be understanding as to why they can't, otherwise you'd be being unreasonable.
If that's the case, why did you make that promise in the first place?
This is why I keep a lot of things to myself, pretend I've forgotten about them. I don't ever forget. I never forget.
It's a lot easier to keep it in, at least you can convince yourself you're still waiting for it to happen. If you bring it up, you're just setting yourself up for that 'please understand or else you're being unreasonable' conversation. I can't put myself through those conversations that I know would happen. I'll keep it to myself. Maybe one day if I lose my memory, I'll forget every single thing in this painful mind..