The rise of women’s education raises their minimum standards for acceptable matches, lessens their economic need for marriage and, in theory, increases the chances that they may choose not to many (van Bavel, 2012). Less well-educated men are likely to be the main losers, as they are more likely to remain single than any other group (De Hauw et al., Married couples and civil unions are the most common arrangements, but about 10% of people aged 20 and over OECD-wide - i.e. one in six of all partnered adults - cohabit informally.