I can't imagine the circumstances where that's true. In general, you'd have at least a few hours to decide and change your mind. In most cases it wouldn't happen at all unless you actively show your interest in that other person.
Maybe when you're drunk and a lady just throws herself at you out of nowhere? I don't know how I would call such a person though ... lucky bastard?
Humans are hard wired to eat, fuck, fight and flee; everything else takes deliberation. That said, you may be right and I'm not inclined to quibble this particular point :)
I can't imagine the circumstances where that's true. In general, you'd have at least a few hours to decide and change your mind. In most cases it wouldn't happen at all unless you actively show your interest in that other person.
Maybe when you're drunk and a lady just throws herself at you out of nowhere? I don't know how I would call such a person though ... lucky bastard?