Why is this girl not replying me?

So I met this girl online and we started talking, flirting a bit and having fun. We talked about our hobbies, views and beliefs, and most of em matched. Suddenly, after 3 days, she stopped replying me altogether. She’d check out my stories and stuff, but not even check out my last message. this has been going on since 2 days. Why is she doing so? We ended our chat on a fun note and she was very responsive to my texts all the time.
Why is this girl not replying me?
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