Although women have served at the front lines of litigation efforts in the emotional debate over same-sex marriage, the issue's most vocal opinion leaders have been men, often leaving the impression that marriage is the preoccupying goal of one sex more than the other. Yet of the close to 5,400 couples who have married in Massachusetts since last May, a figure that represents nearly a third of all same-sex partner households in the state identified by the census, almost two-thirds of the couples have been women. Boston was one of the few cities and towns in the state where male marriages outnumbered female ones.