One day this girl decided that having her friendship rejected was too much for her. So she went out of her way to try and hurt the person who wouldn't let her have her way.
In doing so, she dragged more than just herself and the other person into it: she dragged her professional credibility. The girl forgot that the person she tried to hurt knows a lot of people. And that this person is quite effective at networking and ensuring that the message gets out.
Thus, in neglecting to realize all of these factors, the girl not only damaged her own reputation, she ruined her chances of getting in front of a potential top employer.
Moral of the story: Think long and hard about what kind of revenge you seek. It can end up hurting you a heck of a lot more than the intended victim.