ida ▁Society . ▁ ▁In ▁at ▁least ▁The ▁Moon ▁Is ▁a ▁Har sh ▁M ist ress ▁and ▁Friday ▁it ▁is ▁called ▁" line ▁marriage ". ▁ ▁In ▁several ▁of ▁her ▁H ain ish ▁Cy cle ▁stories , ▁Urs ula ▁Le ▁Gu in ▁describes ▁a ▁type ▁of ▁four - person ▁marriage ▁known ▁as ▁a ▁sed oret u , ▁pract iced ▁on ▁the ▁planet ▁O . ▁ ▁In ▁this ▁arrangement , ▁two ▁men ▁and ▁two ▁women ▁are ▁married ▁to ▁each ▁other , ▁but ▁each ▁member ▁of ▁the ▁marriage ▁has ▁a ▁sexual ▁relationship ▁only ▁with ▁one ▁male ▁and ▁one ▁female ▁sp ouse . ▁ ▁In ▁James ▁Alan ▁Gard ner ' s ▁book ▁V ig il ant ▁( nov el ) ▁the ▁protagon ist ▁is ▁part ▁of ▁a ▁group ▁marriage ▁with ▁multiple ▁men ▁and ▁women ▁involved . ▁ ▁See ▁also ▁ ▁C oh ab itation ▁in ▁the ▁United ▁States ▁ ▁PO SSL Q ▁ ▁Proposition ▁ 3 1 , ▁a ▁novel ▁by ▁Robert ▁R immer ▁ ▁Sam en lev ings cont ract ▁ ▁Types ▁of ▁mar ri ages ▁ ▁References ▁ ▁Notes ▁ ▁Bibli ography ▁▁▁▁▁▁▁▁▁▁▁ ▁Mur d ock , ▁George ▁P . ▁" E th n ographic ▁Atlas ▁Code book ", ▁derived ▁from ▁Eth n ographic ▁Atlas ▁▁▁ ▁Category : S ex ual ▁f idel ity ▁Category : Pol yg amy ▁Category : Types ▁of ▁marriage <0x0A> </s> ▁Green T ech ▁Autom ot ive ▁( G TA ) ▁is ▁a ▁U . S .- ▁based ▁autom ot ive ▁manufact urer ▁dedicated ▁to ▁developing ▁and ▁producing ▁