A nem törvényesen házas, de életvitelszerűen együtt élő párok esetén a leggyakoribb a domestic partnership, illetve common-law marriage. Az USA-ban az egyes államok törvényei szerint eltérőek lehetnek a jogszabályok, de a domestic partnership igen elterjedt fogalom. Harmadik variáns lehet a cohabitation relationship.

"A domestic partnership is a legally-recognized relationship that offers non-married couples the same or similar benefits as those provided to married couples. Click on the links below for information on domestic partnerships and the benefits they offer, including a look at state and city laws on domestic partnerships. (Note: Domestic partnerships are not recognized in all states.)"
http://family.findlaw.com/living-together/living-together-do...

"Common-law marriage, sometimes called sui juris marriage, informal marriage or marriage by habit and repute, is a form of interpersonal status that is legally recognized in limited jurisdictions as a marriage even though no legally recognized marriage ceremony is performed or civil marriage contract is entered into or the marriage registered in a civil registry."
http://en.wikipedia.org/wiki/Common-law_marriage

"Marriage may not be right for everyone. For a variety of reasons, some couples choose to live together without the benefit of a legal union. There are legal differences between marriage and cohabitation relationships, some of which are summarized below."
http://family.findlaw.com/living-together/living-together-ba...