So much of life's stress and strife comes from unmet expectations.
When one thing is expected and another happens; when a promise is assumed and not met, there's a jarring shift in your reality from a reasonable presumption to a clear and present disappointment. The bigger the event, the larger and longer the build up, the greater the risk (and anxiety) of a let down.
There are ways to deal with this. Be more clear about the expectations. Communicate them early and with specificity as to time, order, leading events, and pre-conditions. Mark each step accomplished along the way with check-gates and go / no-go decisions and reviews with the other parties.
You can also learn to deal with disappointment. Life has its ups and down. Look up from the present situation toward the distant horizon and realize that things will work out in the long run. Or simply handle it through emotions, be they depression or anger, those great common methods of dealing with the human condition. Bottle them up or let them out. Who is at fault? Should we play the blame game?
Sometimes, though your expectations are just and reasonable, the other party simply lets you down by having wholly different and altogether valid goals of their own. This happens more often than any of us would like. That's life, but still, it's not fun to learn these lessons the hard way.
What I'm trying to say is I'm taking the kids to see Star Wars: The Force Awakens this afternoon, and you'd better not screw it up, J.J. Abrams.