Among other poorly-supported and inconsistently-reasoned arguments, Stephen J. Heaney puts forth the claim that “a vow…before the community to engage in a project that is greater than the couple” and “an expression of the desires of two people…[which] the community must support…whatever they choose–to have…children…or not” are in direct opposition: “To accept one definition, one must reject the other”. [I didn’t intentionally change the meaning with all those elisions–just trying to make the statements a bit more concise; the original statements make up the entire 2nd paragraph of the source.]
A little diagram: