What is the reason behind this?

I sent a message to a girl i was together in the uni but she left uni for some reason i still did not comprehend. She never me a message even though we were friends kinda and went for coffee back then. But after she left we didn't talk again once we met outside because she was with her friend for coffee and we talked for a while but that's about it. And yesterday i sent a message and she replied instantly but question on question. And then left me on delivered until today and is online but doesn't reply still. I don't understand her issue. She follows me too but never likes my posts i don't understand.

What is the reason behind this?
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