It used to be the norm back before say, the 70's and 80's, for a woman to stay at home, not because she was lazy or didn't want to work, but because she wanted to be a homemaker. Which, believe it or not, is still a valid "career" imo. It's hard to work full-time and devote yourself to your family full-time. And, no matter what the job sharing is like in a 2-working household, I still say the brunt of the homemaking falls on the woman.
I was fortunate enough to be able to stay home with my son for 8 years when I was married. And I was a very busy stay-at-home mom. I filled some of my free time with volunteering which was very satisfying. Did I feel guilty that my husband was shouldering all the financial burden? Occasionally. But then I looked at my contribution to our family and that guilt was gone. My priorities were not divided between an employer and my family. I could devote myself 100% to my home and family and that took alot of weight off his shoulders so he was free to concentrate on his career.