"Interpreting anyone's marriage - a neighbor's, let alone the president's - is extremely difficult." — Jodi Kantor

I spent a lot of time in the White House in the public areas where reporters are allowed to go, but I spoke to people about the private quarters as well. Some of the things I learned were small, novelistic details. For example, the fact that there were still pet stains on the carpets from the Bush cats when the Obamas moved in.

Every presidential candidate highlights patriotism, but Mr. Romney's is backed by the Mormon belief that the United States was chosen by God to play a special role in history, its Constitution divinely inspired.

I guess there were things about the Obamas I discovered that I do think are universal to marriage. I found it very interesting in my reporting that their most difficult periods in the White House almost never seemed to coincide. When one was down, the other one was holding it together. In my experience, that's true of marriage generally.

Interpreting anyone's marriage - a neighbor's, let alone the president's - is extremely difficult. And yet, examining the first couple's relationship - their negotiations of public and private life, of conflicts and compromises - offers hints about Barack Obama the president, not just Barack Obama the husband.