Even if the single woman earns more than a married woman. For the most part, a married couple should have more disposable income after living expenses than her single counterpart. Married couples have a greater per capita net worth than their single counterpart.
In our case, because of choices we made together, my wife earns a little over 10K less than she did when she was single 5 years ago, but because I could depend on her to carry health insurance and she has more flexible schedule, that helps our family, I was able to switch jobs aggressively and I earn roughly $50,000 more than I did before we got married. We are both better off.
https://www.forbes.com/2006/07/25/singles-marriage-money-cx_...
https://www.google.com/amp/www.today.com/amp/money/why-marri...
Once they are married, the couples also are able to take advantage of economies of scale – anything from buying just one dishwasher to relying on one another’s health insurance. That allows them to build wealth more quickly than their peers who are single, divorced or living together romantically.
For example, a married man may be able to work 12 hours a day to please his bosses and get promoted, because he and his wife can divide household duties so he can get ahead. That’s not as much of an option for a single parent.