David Wilcox's Strong Chemistry caught that feeling perfectly:
I got a weakness for strong chemistry
One touch - all my resolutions change
I can say this is no good for me
But I'm back for more of the same
High on the ecstasy - medication against the pain
Our bodies fit desperately together
Like a needle against a vein
I think it's interesting you associate the feeling you get from her with love... 'cause it shore don't sound like love to me! I read "He's Just Not That Into You" a few years ago, and while it's written for women, there are some truths that may help you. If someone is into you, they will: be there when they say they will, regularly stay in touch, want to be with you, etc., etc. It sounds like she's just not that into you... but wants to string you along, just in case her current playmate doesn't work out. I can tell, you're better than that!
Hope you learn to find that love you seek *within* - then it won't be affected by what anyone around you is doing.