Why was this woman extremely rude to me?

I remember working at this grocery store a few years ago and there was this one co worker that was extremely rude to me. She would not talk to me when I spoke to her but responded to other people, she would not dare look at me while I’m talking to her while we’re working and I remember she completely ignored me when I helped her take out her groceries. Her friend was nice but she wouldn’t talk to me. It honestly took all my will power to not punch this woman in the face, lol.

I was just doing my job and being nice but what she did to me was hurtful. Why was she so rude me? Everyone in the store likes me and talk to me except this woman.