importance, from where?

How much importance should I get? From whom? Generally, if I don't get the expected importance from a person, it disheartens me.
So I always try to keep 0% expectation from anyone. But I don't know how; in my mind, maybe I always want some importance.
It hurts when I see people who think about me and come to me in their bad times, and then forget about me in their happy times. I'm trying to take it easy. I shouldn't expect anything from anyone. But I don't know; maybe my absent-mindedness wants a lot.