I do my best writing after great disappointments.
What I learn, over and over, is that disappointment stems from expectations, not from outcomes. It isn't what happens that matters, it is that what you wanted to happen didn't. And the cruel thing about that is that the reality of the situation is lost in the expectation. In the disappointment.
Now that does not mean we shouldn't have expectations. Great expectations. But rather that we need to strive for expectations, not expect them. As goals, or desires, expectations are good. But they have to be inward focused, not outward. We need to expect great things of ourselves, not of others. If we have expectations of other we will surely be disappointed. Because we don't necessarily share our expectations. And without shared expectations, we can't assure mutually satisfying outcomes. One person's disappointment is another person's business as usual.
They say in Zen that the best outcome is the one that was meant to be. Not the one we desire. Our job is not to work outwardly to an outcome, but to work inward to prepare ourselves for the outcome that was meant to be.
Acceptance, not control.
I learn this lesson over and over.