Why girls do that!!!??

Boys do it too. It's called "growing up".

Are you sure she's "single"?

Sounds like she may be in another relationship and just comes around for an ego boost or for outside attention.

OR

She's not ready or she's afraid to get into a relationship.

How old are you? There isnt't much to go on here.

Showing interest (in an undisclosed subject) that you both share? Isn't the same thing as being romantically and/or emotionally interested in you as a prospective partner.

Or she could be fickle. I suspect that she's human. Boys and men also share this annoying wishy washy behavior as well. So please don't generalize.

Yup, im sure she is single.we are both 18.
Thanks

Sometimes yeah she goes romantic.i could not describe what does she she want from me i like her but afraid to tell her sometimes i think tht she likes me too but then again her attitude comes up and then we dont talk to each other for 6 to 7 months but then everything seems normal and we start to talk agaim.

Thanks