it's the helpless feeling when you constantly get your hopes up and then repeatedly get crushed. 'i've got my hopes up again, oh no, not again.'
and you can't tell whether or not the person actually cares about you but you think about them constantly. 'i hear it inside my head all day.' you're hoping that maybe they actually care but they just don't show it...you hope. wanting something so badly and having no control over the situation.