A girl chased me for a couple of months but now stopped, and I like her but it seems she ignores me, why and what should I do ?

I rejected a girl ( a friend of her ask me out) and she tried to avoid me but then a week later she was chasing me for 5 months.
-we were staring at each other
-she would sometimes look down and smile or look nervous
-her friends were staring at me
-she often walked back and forth at the places where i was to grab my attention.

But then i graduated and she stopped chasing me cause she wouldn't see me again.

I've sent her a friend request to at least have a connection with her but she rejected my request

Now she post things like:' I wish I've never met him'. And when someone ask her if she knows me she just says no. (We have never talked though)
A girl chased me for a couple of months but now stopped, and I like her but it seems she ignores me, why and what should I do ?
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