Girl's Behavior

Why did she reject me and then act all "possessive" when I talk to other women?

I asked her out a couple months ago and she's very pretty but I'm going to be honest, she's a bit insecure and immature. She said, "I'm sorry I don't view you that way." I was like okay I wish you well with your life and career. After she rejected me, I started talking to other girls and when I would she'd come up and ask what we were doing and interrupt us. I took her to the side for a minute and asked her to stop acting like child which she get upset about. Also she'd try to get me jealous talking to other men, but it doesn't affect me whatsoever so I just ignore her. Look here's a question IF I ASKED YOU OUT and you said no. Why would she act like I'm her boyfriend or something?

Why did she reject me and then act all "possessive" when I talk to other women?
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