unmarriage
/(ˌ)ʌnˈmarɪdʒ/noun
1The state, fact, or condition of being unmarried; lack of marriage.
- In recent use sometimes with reference to relationships or partnerships resembling but not formally constituting marriage..
2As a count noun: a relationship or partnership resembling but not formally constituting a marriage.
Origin
Mid 19th century; earliest use found in The Lancet. From un- + marriage.