Cohabitation, sexual partners who live separately, extramarital affairs, promiscuity--no matter how close the relationship may be to marriage in reality, none of them is counted in the statistics.
譬如同居、不同居但維持親密男女關係，或一男多女、一女多男的外遇，即有全部或部分婚姻之實，卻因沒有名份，而被排除在統計之外。