When does wrong become right?

I think it's quite interesting this process of having expectations to people/events.
I just experienced a dissapointment recently because I had built up unrealistic expectations to a person. Actually, that person hadnt given me any reason to do so, but the events coming up led me to believe more was to be expected.
And of course that was not the case.

But what strikes me as interesting is this.. even though I was expecting something more, deep down I knew nothing would happen. But I somehow overlooked it. It kept popping up in my mind "it's not gonna happen" but I still went on keeping high hopes, for something that was not there.
Why did this happen?
Why did I build up an idea, hope, an expectation when deep down I knew it would never be?

Is it the fact that I'm searching for dissapointment?
or do I want to believe I'm wrong?
Or do I dare to hope without reason? but is that "healthy" then?
if there is no logic, reason, chance... why build up something that will be taken down, potentially a harsh experience?

It's not that I'm dreaming big,
it's not that I'm setting realistic expectations,
it's not that I'm reading situations right...
it's more that I'm being silly, trying to believe or trying to hold on to what could be/what was.
and that's not so good.
or is it?
I found this very interesting as I feel the dissapointment today.. still sad that my expectations were not met.. and that I should maybe have listened to "myself".
well, you live some you learn some!
or what?

-with love-