Tomche- I agree a portion of the crisis may be the desire to marry younger, although I dont know the stats from 40 years ago.
But to respond to your post, not all people are getting married.
Secondly, even if the proportion is the same, if for example 5% dont get married, 5 out of 100 and 50 out of 1000 is the same proportion. But 50 unmarried is a larger number, hence a crisis.