The percentage of people aged 16 and over in England and Wales who are married has fallen to its lowest level since 2002, official figures show.
In 2015, 50.6% of the population was married, compared with 54.8% in 2002, the Office of National Statistics says.
The second largest category - single, never civil partnered or married - grew from 29.6% to 34.5% during this time.
"Cohabitation has become more common as an alternative to marriage, especially at younger ages," the ONS says.
Although marriage has also declined among the middle-aged.
The divorced or widowed made up a smaller proportion of the total population in 2015, at 8.1% and 6.5% respectively, the widowed population falling from 8.1% in 2002, after continuing increases in life expectancy, particularly for men.
The smallest group was the civil partnered, making up 0.2% of the population aged 16 and over in 2015.
ONS statistician Pamela Cobb said: "Just over half of the population aged 16 and over were married in 2015.
"This figure has steadily declined since 2002, which could be associated with a rise in cohabiting among those who have never married or formed a civil partnership."
In 2015, 26,023 people - 0.1% of the married population - were in a same-sex marriage 13,150 (51%) men and 12,872 (49%) women