One in nine Korean men aged 45 to 54 have either decided to stay single or are having problems getting married.

Analysis of 2015 census data shows that some 10.9 percent of men in the age group have never been married, compared to just five percent of women in the same age group. This is the first time that the rate has risen above 10 percent.

In 1985, there were almost no men or women in the age bracket who had never been married, at 0.4 percent and 0.3 percent. But the proportion started rising steadily after 2000.

Lee Sang-lim at the Korea Institute for Health and Social Affairs said, "The surging number of middle-aged people who stay single all their lives appears to be due to economic slump that has persisted since the Asian financial crisis some 20 years ago, which made it difficult for many to find jobs."

Another factor is changing social attitudes where marriage no longer looks like the be-all and end-all, Lee added. The growing number of women in the workforce also meant that more of them decided they can manage economically without a husband.