The Evolutionary Case Against Monogamy, Ctd

A reader writes:

How do you decide you have an open marriage?  It is much better to do it before you get married.  One of the things I most love about my husband is his honesty and clarity of thought.  We have been married for 20 years.  Before we got married we went through the Catholic Church pre-cana program.  It was very good and helped us define what we thought marriage should be.  There was a very good discussion group about sex.  Since the "mentors" in the group were a good bit older...