Female friend confusing me?

I’m friends with this girl and she would only flirt with me when we was alone but when in a friend circle she’ll act cold, so one day i asked her out and she said she was dating someone else but she would still talk to me and flirt. After awhile we started texting less and when I would text her she would reply but the convo would be quick. Now she acts so cold towards me and not others
Female friend confusing me?
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