This question came up in relationships.SE (still in beta) in this lengthy thread (which I hope you can get access to).
Basically the disagreement goes as follows:
Telling somebody with a crush
It's possible that your crush object may never see you in a romantic light
will let them disregard the 'never' in favor of "possible", because of what DVK calls "confirmation bias" (see note at the bottom). So they would draw possibly false hope from it.
The presupposition is, that people with a crush on someone generally are delusional, at least with respect to said crush, thus suffering from this "confirmation bias".
Now I disagree with the presupposition, but want to put the question, whether it's true or not, here, to ideally get a definitive answer.
Note from DVK's comment:
As a side note - I'm aware that "Confirmation bias" may be a technically incorrect term - call it "Wishful thinking" if you prefer. Basically, the fact that a person with a crush will only hear facts, or interpret anything they hear, in a way that is positive to their desired outcome.