Marriage became much less popular in the second half of the 20th century, with the number of first marriages in the UK declining in the 1970s, despite the population continuing to increase
There have been more dramatic fluctuations in the numbers of marriages (such as during the second world war, there was a dramatic peak in 1940 and then a dramatic slump during the rest of the war)
Since then there has been rather more fluctuation with some years seeing more marriages (partly fed by civil partnerships and same-sex marriages and partly by changing trends, with celebrity and royal weddings)
Giddens' argument is generally used to explain why couples may be less concerned about divorce and remarriage than previous generations, rather than an explanation for not getting married in the first place
Approximately 3% of families in the UK are cohabiting couples, so while they are more numerous than lone-parent families and have more than doubled since the mid 1990s, they are still massively outnumbered by married couples