Originally Posted by preciselove
Part of the reason many marriages end is because while they may not be openly looking for new people after enough time they will randomly meet someone more compatible and start questioning their relationship - "Why isn't Joe more like Steve?" . Open polyamory is like this except you are putting yourself into the game over and over again, increasing chances of finding someone "better". However polyamory at least gives you the option of being together in a group which is a lot better than the monogamous path - the end of the relationship.
I disagree that the "mono path" is the relationship ending, nor that meeting someone "better" is a major factor in mono relationships ending. Many times, situations like that can be an impetus for healing the relationship or marriage, because you see what's possible and start asking for it. Also - if, in a committed mono relationship, one meets someone else, compares them to their partner and is tempted to leave, there usually is trouble brewing in the relationship already. Another person didn't cause it.