This article is from the Polyamory FAQ, by firstname.lastname@example.org (H. Wilper) with numerous contributions by others.
Some do, some don't, just like any other kind of relationships.
Some folks on the newsgroup have been together for many years;
some own houses and have children together. Being polyamorous is
no guarantee that relationships will be easier, though there can
be advantages to shared joys and shared sorrows, as the old