Anna Hundert I wanted to argue one point: mating rituals ARE an exchange. It’d be silly to assume that if a guy buys you dinner you should feel obligated to go home with him, but as with any expression of generosity, ettiquette calls for some form of reciprocity. A simple touch on the arm and a thank you is an example. There are also some circumstances where reciprocity is not required, i.e. a guy can’t go around buying strangers things and declare that he’s been morally wronged if he gets nothing in return.
On a similar note, it’s justified to feel frustrated if a someone takes advantage of your generosity. But in that circumstance you’ve just got to accept you’ve been conned by someone of poor character, or taken a risk that didn’t pan out the way you wanted it to. Acting out that frustration violently is an absurd escalation. And to think you deserve sex forever once it has happened once demonstrates a poor understanding of relationships.
I think the main issue is that some people feel that they deserve something that isn’t theirs to take, which is cleverly illustrated with these analogies.