That is beginning to change, Dr. Cole said, as life expectancy increases, and a generation more sexually liberated begins to age. Nursing homes are being forced to confront an increase in sexual activity.

And despite the stereotypes, researchers who study emotions across the life span say old love is in many ways more satisfying than young love — even as it is also more complex, as the O’Connors’ example shows.

“Young love is about wanting to be happy,” she said. “Old love is about wanting someone else to be happy.”

Young brains tend to go to extremes — the swooning or sobbing so characteristic of young love. Old love puts things in soft focus.