Humans is interesting folk. On the one hand we like to group together, as in following fads and suchlike. On the other, we like to keep our distance. That's why I find it interesting to go into popular coffee shops and see people interacting on their fad-favorite electronic devices, fashionably avoiding contact with each other.
I noticed another thing at a coffee shop recently. The place had arranged its seating so there were two benches along two walls, meeting at a right angle. Opposite the bench were tables arranged in a row. It would be possible to sit right next to a person.
But that didn't happen until one had to. The benches were empty when I got there and as they filled they followed the urinal rule. There was at least one empty space between users until crowding meant one absolutely had to be right next to someone.
Perhaps it originates in some genetic thing. Like avoiding incest or something. Be in a tribe, but don't get too close to anyone in the tribe.
You'll be happy to know modern technology has recently come up with an app for that too. The anti-incest app. It's available in Iceland. Seems the nation's 320,000 residents, confined to the island for generations, are often related because of the inbreeding such confinement causes. With the anti-incest app, prospective partners just have to bump their phones and they'll hear an alarm if they're too closely related.
I wonder if you can hack it. To set off an alarm even if you aren't related, but just think the guy's a creep.
Instead of begging off with a lame "I like you as a friend" excuse you could say, "Gee, I'd love to go out for coffee... but my phone says never caffeinate with cousins..."
America, ya gotta love it.