How do you know if a girl is playing hard to get or if she doesn't like you?

I really like this girl, but I don't know if she is interested in me or not. She tells me she has a boyfriend, but I think that she might be lying. We met a couple of times when she said she would be with her bf, and she just made a lame excuse. Does this mean she is trying to avoid me?How do you know if a girl is playing hard to get or if she doesn't like you?
Yes.