Not that anyone has done this here but I do get annoyed when people call a genuine one sided emotional bond a crush.
In the American vernacular, at least, that is exactly what a crush is, a one-sided emotional bond. Or is the situation you are describing one where a person has let the other one know how they feel, find they do not feel the same way in return, and yet still cling on and keep trying? If that is the case, I agree. That is something very different from a crush, more of a creepy stalker situation.
What you're describing sounds like the friend-zone.