In many ways, the emotional and economic self-sufficiency of unmarried life is more demanding than the state we have long acknowledged as (married) maturity. Being on one's own means shouldering one's own burdens in a way that being coupled rarely demands. It means doing everything--making decisions, taking responsibility, paying bills, cleaning the refrigerator--without the benefits of formal partnership. But we've still got a lot of hardwired assumptions that the successful female life is measured not in professional achievements or friendships or even satisfying sexual relationships, but by whether you're legally coupled.