Definitely the most unique herd, but they all still love and support one another.  
Luna is married to Sombra as king and queen. Tempest is her ever loyal captain of the Lunar guard and more romantic lover. Tree hugger is married to her sweet Zephyr, and Lunas royal consort and nanny for all their children. While not many agree with their chosen life style their herd is strong and new. Herds exist within pony life but it is very uncommon for royals to be in a herd, and as for unicorns ot is looked down upon since they are more independent as a species. Pegasus normally have a flock instead of joining herds, and Umbrum normally travel i stead of staying put in a singular place for a long period of time. But of course this does not matter to them.