Left unchecked, our expectations have a way of ratcheting up. They keep doing so irrespective of the reality of the situation.
The natural result is one or both of disappointment and frustration.
So, it helps to pay attention when we experience these emotions and to use them to diagnose if they were caused by the ratcheting up of our expectations.
If they were, it may simply be time to reset and recalibrate to re-enable constructiveness and progress.