Recently, I've been getting to know this girl who has a boyfriend in another state. Flirting, but no hooking up (yet). I've been using the boyfriend destroyer tactic of constantly building the other guy up and constantly taking myself out of the running ("we'd be terrible together, I like to sleep with the window open"...etc)

I mainly have an interpretation question. I said something about not wanting her to stay in a relationship, to which she replied "I think you might need to let this sit. Even if you don't want to." I blew her off after that.

That to me, seems like it could go both ways? Clearly, if this was a "hell no" I'd like to think it would be a more definitive, but "I think" and "might" makes it seem less surefire.

What do you fellows make of that? And, how would you escalate after that?

You shouldn't have said it. You did the exact OPPOSITE of Strawman. You're not trying to make her your GF. You should be creating opportunities to isolate her at your place so you can fuck her "where nobody will find out".

Girls make decisions with their clitoris, not their hearts.