Ive got a Hb but why is she tring to get me gelouse?

Hey mates now ive got a hb that has the things i wanted in a girl okey but reasently shes been telling me things like her ex bf wants to go to the cinema with her and i told her look your with me i wouldent go and she said she wont but she was like saying no but now hes a friend and if he dose try something  i will back off just like i did last time and He knows im with you .
I told her i trust her.

Any way my main question is why do girls do that to get us gelouse ?

I never try to impresse no need for it i only say something like that when the convo gose towords that are i odnt make it go there for nothing.

As i can see shes tring to see how far she cn push me about talking about something or doingsomething i told her beware if you do something im gone if so.

i can tell shes in to me becase she calles me , seands txt msg and gose on msn.

I think im there for her to much i think im tinking about it that i should by a bit more busy so she thinks she has me when ever she wants.