I don't understand why my schoolmate is afraid of people.

She can't trust people around her (not even her parents) and when she goes outside she gets scarred if somebody gives her a little bit deeper look or if she sees a guy (or a group).

I can't understand what is happening and I wish I could her.

The phobia that your friend has is called Anthropophobia which is basically a social based phobia. Her parents have to recognize that she has this and get her help. You can't help her.

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