A recent Pew Research Center study found that barely half of American adults are married, a historic low. More striking: Only 20 percent of 18- to 29-year-olds are hitched. It’s now standard for a woman to spend years on her own, learning, working, earning, socializing, having sex, and, yes, having babies in the manner she ? and she alone ? sees fit. To be more precise: We are living through the invention of independent female adulthood….paragraph breakMake no mistake, this is a seismic shift.After a long history during which living solo would get you labeled a pathetic spinster or, if you were lucky, a sexual iconoclast, being recognized as an independent person rather than as someone’s daughter, wife, or mother is a new, shiny kind of liberty for women, one that has unlocked all sorts of doors.  ~Rebecca Traister, “Love and the Single Girl: The Single Girl Revolution,” May 30, 2012, MarieClaire.comMarie Claire, www.marieclaire.com/sex-love/single-girl-trend