Great film, could someone help me with a question?

Why did she snap when the "nice" guy tried to have sex with her and started to look at her primary sexual organ, or what should be there, with the help of a lamp? Was it because she realized that though she has human skin, she does not have the related organs and thus cannot sexually perform?

Amazing film. While many people say that the beach scene freaked them out, for me it was the end when the logger assaulted her, attempting to rape her for her looks and then running away once he discovers what's under her skin.A brutal depiction of how our worlds works and it goes very well with the beginning when she is at the shopping mall with all the beauty products.