Girl's Behavior

Does a girl just want a fun time or she started avoiding me for a reason?

So there is a girl with which I was chatting little bit for couple of months. Nothing really special, sometimes she sent me a selfies of her or pictures of her with friends to initiate a chat, sometimes I was the one who starts it. During the time i developed feelings to her maybe she is the one i want to be, but never told it to her directly myself, but we have couple of friends in common and one of them told that to her.
From that moment she changed, never write first and responding cold and short kinda trying to avoid me, unless we meet by surprise on our nights out with friends, then she acts friendly and warm (maybe alcohol doing its job). Could someone explain what is going around with me and her? Should I try to do something? I know she liked me at first or until that point she found out I have feelings to her

Does a girl just want a fun time or she started avoiding me for a reason?
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