If a woman thinks she's been raped, then she has been raped.
The local police may not decide to move forward with the case because of the objective facts, and may not deem it a legal case of rape. However, if the woman feels she's been violated, who has the power to tell her she hasn't? No one, because in her mind, she'll always think that she's been raped.
This is not an objective measure of rape by any means, nor a legal one. However, the person the most affected by a rape is the one who was raped (or believed they were), so the definition of a one-side perceived rape fits for the person who it applies to the most, the "rape" victim.
The woman believes she has been violated. She was unable to stop unwelcome sexual advances, and thus the rape has occurred in her mind. The police probably won't agree with her, but just because she failed to stop the person who wanted to have sex for her, or provide some evidence to make the guy culpable, that doesn't mean she wasn't raped.
And recons, that definition doesn't have to reflect fact. For the only applicable person that this definition is important to, it worked.