The gap between expectation and reality is where all story conflict resides. I learned this by reading the excellent screenwriting manual Story by Robert McKee. Perhaps "learned" is not the right word, because I knew it already, but I didn't have such a succinct way to define it.
Most of life follows this rule. We expect something, and when the reality differs from what we hoped would happen, we have a problem to deal with. In his book, McKee talks about the difference between character and characterization when it comes to writing, but I think the definitions are also true of life as well. He says that characterization is all of the external things we see a person doing, but character is revealed when pressure is placed on a person to make a decision.
He states that choosing between right and wrong is no choice at all, because every person will choose good over evil, or at least their version of what is good. The interesting and real choices we face are much more complicated than that. They involve choosing between two things that are good, but we can only have one of them. Or choosing between two things that we don't want, but have to happen to us. Those choices, made under pressure, define who we really are.
Ever since I read that, I've been noticing how true it is in my life. The gap that widens between what I want to happen and what actually happens is where I'm forced to decide how I will proceed. Sometimes I'm happy with the decision I've made, and other times I'm disgusted with myself and have to alter the course I am on. We all face these gaps on a daily basis. Over time, the decisions we make form our character. We can present versions of ourselves to the world, in the form of our characterization, but our true character is revealed under pressure.
I like to think in these terms as it gives a sense of gravity to my choices which adds up over the long term. I would like to teach this to my kids, through my actions and choices, but also to describe the gap to them so they understand that there is often a difference between their expectations and reality. If I had known this in my childhood I think it would have helped me find my way as an adolescent and an adult, because I was continually setting myself up to be disappointed by people.
We cannot choose what happens to us, but we can always choose our response when the gap widens and we reveal what we are made of. When we fail to respond as we would have liked to, grace exists for that purpose. We are not perfect and never will be, but hopefully we are growing, a little each day, week, month and year, until it all adds up over a lifetime.