Mitt Romney, described by some as too stiff and passionless to win the presidency, opened up a bit Sunday, recounting how he and his wife, Ann, learned years ago that she had multiple sclerosis.

In an appearance on Fox News Sunday, the Republican presidential candidate recalled entering the doctor’s office and seeing a pamphlet on various illnesses, including Lou Gehrig’s disease, a fatal disease that he feared she had.

“We could see that she had real balance problems and she didn’t have feeling in places she should have feeling,” Mr. Romney said. “And he (the doctor) stepped out of the room, and we stood up and hugged each other, and I said to her, as long as it’s not something fatal, I’m just fine. Look, I’m happy in life as long as I’ve got my soul mate with me.”