"IDIOT! It's not like I'm doing this for you or something..."
Generally, her lover will do something to earn her affection, triggering a loving reaction, but she will then compensate for this perceived weakness by going harsh, where she will either deny or attack her lover. These kind of characters are generally more comedic in nature than characters with severe obsessive love disorder, even though this character type can be played more seriously as well.
This tag, specifically, refers to girls displaying this personality via contradicting actions and emotions. The easiest example is offering a valentine's day gift, but telling the recipient something akin to "It's no big deal, I don't care about you, I just had some extra."
Often, this kind of behavior can result in mixed signals.
The original definition is a girl that starts out harsh towards a guy but as they get to know each other, she slowly changes to a more affectionate personality and generally staying there. The other types came about as a result of various writers trying to copy it.