This trend started in the First World in the 1960s, with all the other immoralities that decade is infamous for having wrought upon society. It was in that period that the birthrate began a precipitous decline that has most sadly picked up ever since. This timeline coincided with the mass entry of women into the workforce. Whereas, previously women mostly were homemakers and stay at home mothers, the feminist movement began insisting women join the workforce and demanded government and social programs pushing society into that direction.
The feminist movement? How about the KOLLEL movement, where the husband abrogates his kesuba obligations?