It can also be a train wreck of great horror. Great care is required, though great good can come of it.
Risking sounding like a broken record to those who have been around here a long time, I do not believe polygamous relationships have any greater potential to be train wrecks than do monogamous ones. For every example of problems in polygamous marriages, one can find a thousand examples of perhaps different in some respects but basically equivalent problems in mono marriages.