Question for the girls. do all girls do this? (guys opinions welcome)?

So i have this friend who is a girl. we have been friends for about 5 years. there has always seemed to be this... well i guess you call it sexual tension between us. ive always kinda noticed it but never really acted on it because she always sends mixed signals. for example she will be kinda touchy feely, but then say something like I missed my chance in the past. or even further more one time she told me she wanted to hook up with one of friends, which really made me think she didn't have that kind of interest in me, and that was okay by me. hell i was even guna go out of my way too hook them up. so anyways the other night we hooked up and did the did deed. but what kinda blew my mind was that she admitted to doing things to **** with my head on purpose. for example i found out she didn't like my friend, she just told me that to basically try and get a reaction from me. and even though this isn't the first time ive noticed this from a girl, im just wondering do all girls do that kind stuff? do they do it alot? and why do they do it?