Did you ever notice that we give certain expectations to our kids like what time to be home, and about some behavior but then we slack on other expectations? We do it with our friends, our families, and in some cases our spouses or significant others?
I admit that some expectations are easier to communicate than others... be home at 6, dinner at 6:30, you do the dishes, I'll cook dinner, etc. But there are some expectations that are not so clear. I have a friend staying with me until they get their new condo, timing issues. I expected them to call if they weren't coming home (they often go to the other side of town to visit friends - late), they thought it would be disturbing my sleep if they called to wake me up. I didn't want to seem like an over controlling mom (even though I am!) and say something, but I lost sleep in worry (if you want I could probably state at least 10 possibilities of things that could go wrong) but a phone call... right to sleep. Eventually I said something, it was so easy.
Believe it or not, it also helps in dealing with a teenager. Sometimes I think "oh, she should know that" but sometimes I don't communicate it that well. If she knows what is expected, it is much easier for her, and me.
There are many more example about how communicating my expectations has really helped me (thanks Sara, oh wise one) and even though I am not even close in marriage realm, I think that it has proven to be a lesson that will serve me well when I do get married.