And I'm saying she's a member of a primitive tribe who thinks being 13 and having sex is fine. To her, she's not being raped.

If you read my comment above in full, I did say what he was doing was reprehensible. Relative to our culture, he's molesting a child, and if it were happening in the US it would be considered rape because we consider people under 18 to be incapable of informed consent. And therein lies the uncertainty of definition, since she was informed and consented.