Why do women seem to want a guy when he already has a girlfriend?

I don’t understand her. We are friends and I asked her once if she see me as her boyfriend. She didn’t say anything and I understood it’s not going to happen. I moved on with my life, we only friends. Now I have a new girlfriend and because of that my friend don’t talk to me any more and ignoring me like I did something wrong.

She never told me she like me or want to be more than a friend, I was in the “friend zone” only. Please help me to understand this situation from a girl point of view.