Mitt and Ann Romney’s marriage is strong because they believe they will live together in an eternal afterlife, relatives and friends say, which motivates them to iron out conflicts.
Honestly, whenever the NYT speaks of Christian theology or sacrament these days, it's as if they're explaining the practices of some odd cargo cult to a collection of curious readers. It reminds me of the tone heard in those old travelogues that used to be shown in movie theaters: "Here are the Tahitians in their colorful native dress. Don't shrink our heads, boys and girls." or "Behold the Navaho trinket salesman. Don't worry, he doesn't want your scalp!" Yeesh.
The part that gets me is that the NYT implies that this belief of the Romney's is something particular to Mormons. In fact, it is the Christian sacrament of marriage as understood by anyone who is, well, a Christian of any type, denomination, or church. That's why marriage is a sacrament; it's eternal.