Blair-Loy's main argument is that cultural schemas of devotion - devotion to work and devotion to family - have enormous power to shape and/or constrain our behavior and more importantly, our identities. These schemas are largely based on a gendered division of labor and heterosexual marriage - the idea that a man will go out and provide, while a woman stays home and cares for the children and the home. For highly educated, professional women, these schemas are at odds. In this book, Blair-Loy explores the ways in which women have both bought into these two schemas and how they attempt to alter them to better fit the circumstances of their lives.
I think one of the most interesting points she makes is that neither people nor companies/firms always act rationally. Women who earned double what their husbands did still gave up fulfilling and lucrative employment to raise children. Companies, rather than work with women to be more flexible and family-friendly, are more likely to fire a woman who wishes to work part-time - costing them a valuable asset. Her argument here is that these cultural schemas are so powerful that they override even economic rationality.
Blair-Loy's respondents are primarily White, upper class, professional women. It would be really interesting to see how working class and poor women navigate these same schemas with fewer resources.