You could say that you already had plans, but would see if you could get out of them... use one of her own lines! Or, you should actually make plans for yourself, join a yoga class, or cooking class, or something. It wouldnt be too bad if you ditched it, you know, because you wouldnt be really letting anyone down, and if you ended up going, that would be cool too. I think that you are right about going dark a little again, just to feel things out.
I guess I gave the wrong finger to the wrong man...