Originally Posted by ngdawg

Yes, but you didn't start out that way-it was a process with a lot of work, compromise, thought, etc., and will take at least as much to keep it going.
It's a delicate balancing act. Too many look at polyamorous relationships as just a lot of sex, but if there's no real friendships, an ability to be just as platonic as romantic, something will give out.
As SM pointed out, most marriages fail at some point. Perhaps one reason is the thought that 'I don't have to work at this as hard now' starts to take hold.
Complacency, too much comfort, etc. and before too long, boredom. If we go into anything with a thought that we better really enjoy this for as long as we can because it probably won't last, instead of sitting around thinking this is forever, maybe more couples/triples would succeed in the long run.