You're getting it man - if this comment's any indication, you're almost there.
The "spell" thing is really a battle of wills right now. She's trying to get you wrapped up, you're trying to get her wrapped up. I call it a "spell" because you're clearly spending a lot of time thinking about her and a lot of time working on her. It may well be she's under your spell as well. But it's not a healthy dynamic for either of you, because you're just frustrating one another.
Telling her you're going to knock off the games and telling her to step up or step out is exactly the right call. It's the only way you get free of the B.S. and the back and forth - communicating to her, "Look, we can hang out, or we can not hang out, but if we're not going to hang out I don't want to keep spending time on this, it's purposeless," (maybe not in those words, but to that effect) is what you need to do.
Call her on her bluff - she's either going to get together with you, or you're going to find out it's only fun and games for her, and you'll turn your attentions elsewhere.
And she won't KNOW you have other women (unless she sees it, or you tell her), but she'll pick up on the behavioral differences between George who's only spending time with her, and George who's sleeping with a couple of new hotties he's just met and for whom this girl is becoming increasingly old news.