I've often thought about the people of my grandparents age who were born in the 1880 and 90s. They never got more than a few miles from home and met a limited number of people. My grandfather and his brother married sisters. Almost everybody in the areas they lived in were related through marriage. There was a very small pool of prospective spouses, yet people of that era, met, married and stayed married until one of them died. By 1920 8 in 1000 couples were divorced. Maybe because they had so much in common. There may have been a few murders but not divorces. It was still rare before 1950, especially in rural areas.
Today, almost 50% of marriages end in divorce. First marriage divorces have dropped from a high of about 40% around 1980 to a current rate of about 30%. Divorce rates from subsequent marriages are much higher keeping the overall rate near 50%.