Well, let there be a lesson in everything. With distance comes clarity, as it always does, and I can see, now that I'm feeling better, what got me.
See, if I go on a shitty date, and I can TELL they're not into me, it's not a surprise. The thing that hurts here is that I couldn't tell. I told a buddy earlier and he said, "Yeah, I understand. I once talked to a girl for 2 hours on the phone and the next day when I called, she said, 'Don't call me again.' What?!? I thought things were going great. It really caught me for a loop."
What hurts is this: how could only one of us be having so much fun? How could I have missed the obvious signs? How can I trust my own judgment if I missed the signs so thoroughly? I'm doomed!
I guess they don't know you so they won't be able to tell your enthusiasm's turned down so maybe there's no real choice other than to be polite and brief.
The takeaway is basically: grow a thicker skin. Be more resilient. Don't put so much weight on the dates that seem good, you still never know where someone is. Let the good date spur hope that there can be more fantastic dates, not fear that this is the last great possibility on earth.
You know, lessons.