What is it called when two individuals live together in a sexual relationship without being married?

When two individuals live together in a sexual relationship without being married, it is commonly referred to as "cohabitation." Cohabitation can involve partners sharing a household and engaging in romantic and sexual relationships while opting not to formalize their union through marriage. This arrangement has become increasingly popular in various societies and cultures, often reflecting changing social norms regarding relationships and marriage.

Cohabitation may serve different purposes for different couples; it could be a step towards eventual marriage, a preferred lifestyle choice, or simply a practical arrangement to share living expenses and responsibilities. Legal and social implications of cohabitation can vary significantly depending on the jurisdiction, including issues related to property rights, child custody, and spousal support in the event of a breakup.