Sedoretus: It's just as complicated as it sounds, but aren't most marriages?

Some people in tumblr fandom have declared July 1 polyshipping day, a celebration of all sorts of ships involving more than two people.  I wrote some meta to post over there, but I thought I'd post it here too to take advantage of LJ's ability to have a conversation in the comments.

( My favorite underutilized polyshipping trope: sedoretu marriage! )