I have no problem with triads/quads/etc. Find them to be the most stable relationship structure, even more so than monogamy (I know four is supposed to be the "most" stable number, at least in numerology, not sure where it comes from, really). So a quad would be the most stable? Maybe? Not important.
I do think that so many couples do group relationships very poorly, which makes it all the more frustrating for those of us who very much consider the needs of all involved.