Is it normal for this girl to be distant or is she being hard to get?

Our families are very close. My stepmom and hers are best friends. I go to her house when my stepmom does just to see her. Iv talkd to her bout her problems one time she started crying and she just gets up says sorry and leaves. I was flirting with her and telling her shes beautiful and she says im a good liar. Another time we were about to kiss and she just gives me a hug. Im getting kind of confused now. Its so hard to get her to talk to me. Shes so shy. I want her to open up to me. After the time she started crying she avoids like conversationa about her issues or she like ignore me if I ask whats wrong.