Great Expectations.

Why is it that we try to hold people to standards that we think we meet ourselves, yet we never let them know we're expecting them to meet them? So if and when they fail to live up to our hopes/expectations, we get upset...I know many of you post on the topic of dating and relationships, so I have a question for you. What are the rules of what is fair game in someone both you and your friend are interested in? If no one has established "dibs", is it just open season and may the best man or woman win?I find myself watching this situation recently with a couple of my friends, one of whom is very open in telling me his thoughts on the topic. He feels like even though his friend didn't really know he was into the girl, the girl did, and by leading them both on, she let him down. Obviously this is helping him to move past her, but the question is whether or not its wrong that he expected her to be honorable knowing she was flirting with two good friends?He knows he wouldn't come between two friends, so can he expect others to meet his own private moral standards?