“We can define singles as legally single or socially single, though the two often overlap. According to the U.S. Census Bureau, over 40% of adults are legally single, including people who are divorced or widowed and those who have always been single. In everyday interactions, what matters most often is whether a person is socially single or socially coupled. People who are in sexual partnerships regarded as serious by themselves and others are socially coupled” (DePaulo & Morris, 2006, p. 251).“Singles often maintain a diversified relationship portfolio, rather than investing so much in just one person” (DePaulo & Morris, 2006, p. 253).“Single adults without dependent children” (Casper & Swanberg, 2009, p. 96).

DePaulo, B. M., & Morris, W. L. (2006). The unrecognized stereotyping and discrimination against singles. Association for Psychological Science, 15, 251-254.Casper, W. J., & Swanberg, J. E. (2009). Single childfree adults: The work-life stress of an unexpected group. In A. G. Antoniou, C. L. Cooper, G. P. Chrousos, C. D. Spielberger, & M. W. Eysenck (Eds.), Handbook of managerial behavior and occupational health (95-107). Cheltenham, UK: Edward Elgar.