“The past few decades have brought dramatic changes in the residential arrangements of romantically involved unmarried adults. Indeed, as sexual activity has become uncoupled from marriage, growing numbers of young couples have begun sharing a home and a bed without the legal sanction of marriage. Cohabitation, as this type of living arrangement is commonly known, has become a normative part of the adult life course…While living together without being married is far from being a new phenomenon, it first drew serious attention in the 1970s and has since been a topic of great interest. It has become increasingly prevalent over the past three decades. In the US, initial estimates from the Current Population Survey (CPS) of 1980 revealed that approximately 1.6 million unmarried couples were cohabiting, more than triple the number that did so in 1970. By 1990 the number of cohabiting couples had grown by another 80 percent, to almost 2.9 million couples. A total of 4.9 million households consisted of heterosexual cohabiting couples in 2000. Despite the dramatic increase in cohabiting couples, at any one point in time the proportion of all co-residential couples who are unmarried is rather small. Cohabitors accounted for only 8.4 percent of all couple households in the 2000 census. Other western countries have also seen rapid growth in the numbers of people cohabiting.” (Sassler, 2007)