Anon,
All I can do is say what it would be like for me. If I'd made love to someone for three hours and he briskly informed me that was all about FRIENDSHIP, when what I really want is a long-term love, I'd be outta there.
Well, not true. In times past, I'd-a been stuck on him like a barnacle, waiting for him to reciprocate my loyalty. You see, one day he would wake up and not be selfish and manipultive. Except, oops, that wasn't just behavior, it's who he was. She made me think of the childlike sexuality of a Melanie Griffith or Marilyn Monroe...that breathy voice. Dunno if your ladyfriend is like that, anyway.
I think her behavior is who she is. And if you want to live with who she is, you can exhaust yourself wooing and screwing (pardon my French but it rhymes). And like any 4-course meal, you'll wake up satiated one day, stagger to the kitchen, and realize that you've been left with the mess.
I'm not awake enough to write good images. I understand the appeal of great sex. In my life, more than once I have had the best sex with the worst people. I've now decided that I would gladly accept warmer, less spectacular but loving sex with a good man, a steady-hearted partner...and count myself lucky I didn't get fooled by the fireworks. Had too many blow up in my face, and this woman sounds like the female version of my various trainwrecks.
So that's why. Voice of experience.
Hope it helps,
Hops