It sounds more like emotional immaturity. Could be behavioural.
Maybe she just doesn't know how to deal with someone being interested in her but not being interested or able to reciprocate.

She sounds terribly similar to a woman I worked with who suffered sever trauma in her teens and was unable to mature past that point.
To all intent and purposes she was a 30 year old woman. But she lived with her parents and wasn't able to make certain decisions for herself. That was particularly pertinent with her personal life as she just wasn't mentally mature enough to be involved with someone as she was unable to give consent to what she did or didn't want.

This, of course is an entirely different set of circumstances, but perhaps the next time a girl says "no" to a relationship at the start, you should just accept her first answer over any and all behaviour that comes afterwards. That way you set your boundaries and it keeps you safe.
No matter how interested or whatever, she gets.

Hopefully given consistent boundaries now, she will eventually understand.
All the best.