So what do I mean by this? What's wrong about having certain expectations of people?

We can expect certain things from certain people, but we must realize that if we base all of our satisfaction/livelihood on how well people meet or exceed our expectations, we are setting ourselves up for misery.

Instead, what we can do is make observations of how people behave and what traits they possess. From these observations, we could adjust our actions accordingly. If we only set expectations, we have no control over whether or not other people will meet them or try to meet them. All that is left is frustration.

This is an absolutely critical step to self-improvement because instead of giving people a responsibility for your own happiness, you're giving yourself more control over it. And this is the way it should be.