Ok my experience of this and I'll make it clear from the get go that I am no "know it all" this is just my opinion from experience.
Right I cant stand women like this but I think her actions are going on what you've already given her. By this I mean... She knows you like her, women like to be the centre of attention so she knows she can sleep in your bed, sit and watch films with her and basically do all the "boyfriendy" or worse still "friendly" things with you... It sounds to me one of two things... Either your in the "LJBF" zone or shes just REALLY nervous ...
If she was a virgin I'd say shes nervous but if shes tasted the forbidden fruit, fcuked another guy then I'd say that it's not going to happen and shes just in the mindset that she gets attention from you so its convienient (cant spell it) for he to keep coming back to you... IE she knows all she has to do is turn her back when your getting to close and you get the message...
The best solution for this???? Go get another girl and test her out... Or if thats not possible then at least make out that you have interest from someone else.
Just say something like "so yeah I was in the canteen earlier and this new girl called blah blah from blah blah asked me to show her round, so i did and we're going to the movies/dinner/her place next week, cool huh?"
And say it in a friendly way like your talking to one of the boys... She'll then either think "oh right hes gonna start seeing someone I need to show interest" or "ah right hes looking elsewhere i will too"
The thing you need to be wary of is that you dont get stuck in the mindset of "one it is" and you've already shown her your poker hand by saying "i like you"
In my opinion theres only one solution here... Shit-test HER ASAP and make her work on you or show her the door, because shes in controll at the moment and if your on a PUA forum surely it should be the other way around??
Good luck with whatever and remember theres something like 13billion girls in the world, if shes an 8 then theres 2 HB sets above her!!!
Numpty
PS... this may sound a bit abrupt but I see these posts all the time from people in college/highschool/university - Whatever and its always the same "but I really like her" etc etc - I just get bored hearing AFCs all the time, its nothing personal...