Don't you mean, "why some women try to make other women look bad?"
Superficial posers can't tolerate competition where other women are concerned even when there's no challenge involved. They seek constant attention, especially from the opposite sex, and love to play center of the universe games. After it's all over and done with, ask them why they treated you so terrible.. In most cases they'll wave it off and assure you it was nothing personal (don't believe it).