100 years ago, when divorce was relatively rare, admissions into mental institutions of women were the same percentages then of what divorce is now!!!!!!!!! Women used to stay because they had no way to support themselves or their children, risking their mental health in the process.
Today, those same women, in really awful marriages, now have chances for education and employment, and thus divorce is a real option. Being divorsed now carries no sigma..... Even in the 1940's if a woman were divorced, she was looked upon as someone sub-human..... Even though those who did the looking wished that they were not in the marriage that they themselves could not get out of.
Years ago, the only employment open to women were nursing, teaching, some sales jobs receptionists and secretaries. Now, women are in university positions, physicians, professors, business execs, and so on.