Hyergamy vs Polygamy

The full article can be found here:
http://econlog.econlib.org/archives/2009/07/the_lens_of_hyp.html#.UXL4ksza6xo.twitter
 
My initial response is, "Well not EVERYONE..." but I do think there's some truth in the article.  Essentially:  Men are fine staying in an unsatisfying relationship as long as they can stray to other relationships.  (Or are fine straying even if they are happy.)  Women leave relationships in which they are unhappy so that they have room in their life to "trade up" - or they leave relationships in which they are actually fairly happy in the hopes or trading up.
I still don't think that applies universally, but I think it can often apply.  It also explains why so many men "cheat down".  They've already got something good at home, they're not looking to "trade up".  This actually explains and reassures me in a LOT of ways.  Because, at least in part, I will find myself thinking, "Why did he risk SO much for someone he didn't even LIKE, much less LOVE?"  Well.  Frankly put, because he could.  It wasn't that she was better, or prettier, or smarter, or richer, or sexier, or... it was that she was available and what's another notch on the bedpost.  He still got to keep me, right?
This also explains why so many women have a hard time (maybe I'm wrong in this... but it DOES seem like a LOT of the Cheaters Anonymous population are female) have a hard time letting go of the other guy.  In some respects, he is better than what is currently on the plate.  If a woman wants "the best" - or at least the better of two choices - and the scales are fairly evenly tipped, it would cause a lot of trauma and drama and upset if this theory about Hyergamy is true.
Something to think on, anyway.