Good lord man, get out of your own head and stop going so "meta." You're not a dumbass. It's her loss, so try to feel a bit of pity for all the crazy women out there.
Yeah, and never mind the fact that a popular dating service is actually called It's Just Lunch! This is like an enigma, wrapped in a puzzle, covered in duct tape.
Nervous will be matched by her, so she'll be looking for an excuse. "Being engaged" or "I have a boyfriend" are common ones.
One way of making sure you're calm for a call is to call three-four other people first, so you get into the "I'm just calling people" vibe.
-Eek
Commenting by HaloScan
