In the past it revolved around marrying to advance your social class. The poor had very limited options since they were treated as if they did not need to get married, so that the poor class could just disappear.
Families and the way they function according to Coontz has been a revolution as great as the Industrial Revolution. Meaning that these changes have had good and bad effects. Separate spheres for men and women have come a long way, this being one of the good effects. Men are no longer the main dominant presence in a relationship. Women can now run a household as well. It can also be a joint effort. If men and women share roles in the family, we get boys who are more empathetic and girls who are beginning to take charge of their futures. This can bring us into a whole new generation of families. We do have the downsides of how easy it is to remove yourself from relationships as well. Since you can leave if you feel it is failing then it removes some of the effort that can be put in a relationship. Love is a tricky thing to focus a whole marriage around, there are a lot of other things to consider as well.
As we have heard from Coontz really great things can come out of change. We do