I know more teachers into this sort of thing than any other profession, have to figure that out some day
While I've always thought monogamy was more of a mythical 'ideal' than anything suitable for real humans, I think being a true 'poly' is a pretty big leap.
Its pretty hard to love someone 'equally', there will always be favorites, and I think if I truly loved another woman as a wife, the love for my wife would diminish and be less 'special'.