Americans fear the startling rise in autism diagnoses—one in 88 kids is diagnosed as having an autism spectrum disorder (ASD)—but few understand the experience of those caring for an autistic child. Fewer still grasp how the burden of this care affects a marriage. Differences in style that seem minor, even charming, pre-kid (a little flakiness, a preference for play over planning, ) can be enraging when seen through the prism of raising a child on the spectrum. Many marriages crumple under the strain...