Romantic couples who live together, but are unmarried, may represent a middle ground in health benefits between those who are married, and those who self-identify as single.[6] However, people live together without getting married for many different reasons; cohabitation may serve as a prelude to marriage. Selection factors of race, ethnicity, and social-economic status predispose certain groups to cohabit unmarried, and these factors also affect the health benefits of marriage and cohabitation.[2]