So, to cut to the relevant part of the conversation, it turns out B has a boyfriend.
Proceeding with caution was a good idea... just as happy to have found out she wasn't a gf prospect BEFORE I said anything to her about crushing on her.
I guess I still have a new friend anyway... cuz I wouldn't have liked her that way if we hadn't clicked, and I'm not about to stop talking to her, that would be stupid, so...
...shame that didn't work out a wee bit better for me (I'm not sure if the disappointment has quite hit yet), but... oh well.
Now y'all know how that one worked out.