And the one, having failed to express anything for thinking the other not interested, causes the other to think the same and therefore to leave.

Hold your cards close.  Show your hand.  Show one card.  Show two.  There seems to be no only answer.  But how much fails to start for the lack in deciding which is the proper course of action?  How many have stumbled because all of us concern ourselves with wondering what the other is thinking rather than simply asking?  It is because even the simple asking can be a showing of our own cards, thus compromising our position. I hate the gamesmanship of it, yet it is there, and it is required when there is more than one and there is no way around it.