Conservatives often assert that same-sex marriage will push us along the slippery slope towards the breakdown of marriage and polygamy. On the contrary it was the stress on procreation that led to the slide to polygamy under Jewish law and custom: both in the Levirate regulation requiring a man to bed his brother’s childless widow; and the insistence on divorce of an infertile wife, or the taking of another wife or concubine (e.g., Hannah, Peninnah, and Elkanah; or Jacob, Leah and Rachel.)

Relationships that are based on achieving ends will fail when those ends are not met. Relationships that are based on mutual love, in which each to the other is an end in him or herself, will endure. As the Rabbis put it: “Any love that depends upon something else, when that something else disappears, the love disappears; but if it does not depend upon something else, it will never disappear. What is an example of love that depends upon something else? The love of Amnon and Tamar. And what is the love that does not depend upon something else? An example is the love of David and Jonathan.” (Pirke Avot 5:19)