[bunderbunder]

Another big assumption: That monogamy is synonymous with marriage. (Or, conversely, that not wanting to get married is a sign of promiscuity.)

During the time period the article talks about, that equation has been scuttled. The gay marriage kerfuffle has led to the invention of domestic partnership as a legal status. It's a serious contender against marriage, since the laws are usually set up such that domestic partners can enjoy many of the same privileges traditionally reserved for married folks, while avoiding many of the laws that can potentially financially punish a couple for getting married.

And it's generally not included in figures about marriage rates. Which means that comparing a marriage rate statistic from this century to one from the previous century is not apples-to-apples.