Do women compete with other women out of insecurity or (the opposite) because of a perceived superiority?

I think everyone knows someone that always has to turn everything into a competition, be it in academics, arts, sports or romantic relationships. There is a woman at my work place that I talked to briefly once about a year ago that seems to have some kind of problem with me. I saw her sneering at me several times for no obvious reason, she would stare me down when I walk past or she would turn around and look over her shoulder at me when she walked past me to give me a gloating smile, she would start dressing more feminine, ignore my work related messages on teams and not pick up calls (in front of my supervisor haha). I might be misinterpreting her facial expressions but the one time I talked to her in person I felt like she looked a bit worried and she kept glancing at my lips for some reason. After that first talk whenever she would run into me she would ignore me or acknowledge me with a „yeah right“ as if I had done something to upset her. With everyone else she is super charming and flirtatious but with me she rubs into my face that she has some kind of problem with me. Why does she act like this? Is she insecure or is she a snob? She is good looking, 38 years old, married mother of 2 children and would die for male attention.

Do women compete with other women out of insecurity or (the opposite) because of a perceived superiority?
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