Complex sentence: Work-family balance in the U.S. differs significantly for families of different social class, with middle-class family issues centering around dual-earner spouses and parents and lower-class issues centering around problems that arise due to single parenting.
Split into simpler sentences: Work-family balance in the U.S. differs significantly for families of different social class. Middle-class family issues center around dual-earner spouses and parents while lower-class issues center around problems that arise due to single parenting.