expectations

I got a call from my dad today and said because of the snow storm, my parents are unable to come down for the weekend. So now, when the news is given to my kids, they will be heart broken. Why? Because their expectations were so high. I have found that if you continually find yourself being hurt or disappointed on a regular basis, maybe it's time you lower your expectations. I now this sounds crazy, but here me out. Then you are not expecting anything from anyone, but if they do come through or give me something, it is a bonus. Perhaps, it's the relative that is ALWAYS LATE to every get together. It then bothers you so much that you miss out on the joy of seeing everyone else. What if you didn't set your expectations for them so high? Whether or not they get there on time then, doesn't affect you. When they show up or don't show up is all the same, you are just glad to see them.
I hope that makes sense and of course I don't apply that to everyone or every situation, but rather have used it with people who may continually let me down. I guess it could be a form of a boundary where I don't let them have control over me or my emotions.