Why did states start to consider liberalizing divorce laws in 1960s?

Social changes in morality, economics, mobility and gender roles are pieces in the mosaic of the history of divorce. Divorce is not new. In colonial America, where society’s norms found expression and a repressive theocratic community, divorce involved grave questions of guilt and innocence. Yet at least as early as the end of the seventeenth century, divorce had become a society issue. In 1629, the Massachusetts Bay Colony created a judicial tribunal for divorce, empowered to issue divorce decrees on grounds of adultery, bigamy, desertion and impotence. Adultery was the primary justification for a divorce, complete with proof of guilt and "[h]arsh social and punishments...for the guilty party."

It is popularly quoted that one in two marriages end in divorce, but divorce statistics can be very misleading. The divorce rate in the United States increased gradually between 1860 and the early 1960s. After World War II, it soared for a time, but there have been increases and decreases over the years.

For reasons still being debated, the consensus about the sanctity of marriage began to dissolve in 1960s. Probably, rising levels of affluence in America elevated expectations about life happiness, and with this came support to change laws that seemed to frustrate that.