Interesting article here that suggests it's not only income that's polarizing but social divide.
http://www.theglobeandmail.com/globe-debate/marriage-is-the-new-class-divide/article23545818/
While MW's articles are often filled with oversimplifications and generalizations, much of this piece runs true in my experience. My wife and I have a stable 16 year marriage, fiancial security has always been a focus, leading us to work smart and hard to pay off the house and focus on education, our kids go take Extended French and music at school, have stable home environments where reading, music (piano lessons at home, sax and violin at school) and learning are central, with tutors where needed, and no screen time whatsoever for the kids except for Friday nights and the weekends, with no tv in our livingroom or any bedrooms (tv is in dedicated tv room), if they need a computer for homework it's the desktop pc in the kitchen. I would say the girls are fit and healthy but not athletic, though one has asked for ski lessons that I might take with her (might be fun). I like my girls to have a strong money sense. We drive old cars, take family vacations twice a year, which are always saved and paid for before we go, and RESPs have been in place for the girls since birth (can you tell that I fear debt, and want the girls to think the same?)
We choose the above life for our family with the objective to giving our girls a headstart in life, as MW's article suggests. I can definitely see that people with different circumstances would face the article's social divide. Yes, you need income to live our life, but we're hardly rich and there's a ton or prioritizations and choices as well.