Plot hole: How is it possible that Diana is unaware of the concept of marriage? She has a grasp of multiple languages and cultures and can recite Socrates. Socrates often spoke of marriage, so even if her people do not marry, it makes no sense that she is completely unfamiliar with this human custom.
Suggested correction: She has never seen a man either. She read about them, but never actually saw one. One might question why she doesn't understand a man if she read about them, and yet she doesn't. Same thing with marriage.
She had never seen a man, but she knew that they existed. She speaks multiple languages, despite never having met someone from any of those cultures. My point is, if she's so well versed in world cultures, how has she never heard of the concept of marriage?
