yes I realize it is not literal, but the structure of that part of the text as you progress from two people in love come up with a plan to always stay together ends up a just so story about how marriage was created.
Does it work as a list of incentives for how marriage came to be a successful institution? Well since it structures it as an origin story of marriage that you realize is an origin story of marriage at the same time you realize this is obviously not at all how marriage came to be, no it does not work. And I mean - for how marriage came to be a successful institution even has the phrasing came to be inside it. How do you explain the lasting success of an institution based on a fairy tale of it's creation - well lots of things are explained as fairy tales but not rationally. This document has a style that argues the author believes they are making a rational argument, which grates.
It's frankly idiotic the more I think about it! Which I guess would be ok if it was something you told your 5 year old when they asked hey how did marriage come to be. Fairy tales can be charming and funny, but I think the author thinks they're being clever and serious.
So now I went back to read more just to be sure they didn't deal with the fairy tale aspect better further in, but it was a waste of time.