Elmer goes to the nursing home where my mother now lives every day. Elmer, 84-years-old and dependent on oxygen following lung surgery several years ago, arrives shortly before 5 p.m., just in time to help Mom with her evening meal.

After dinner, the two of them sit side by side in her room, Mom slumped in her wheel chair, drifting in and out of sleep, Elmer in a reclining chair, resting from the exertion of the trip to the nursing home. He usually holds Mom's hand or rests his forearm on her leg as he reads the newspaper or watches the evening news.

Shortly after 9 p.m., several aides come to lift Mom into bed, and Elmer climbs in beside her, staying there until she drifts off to sleep. Then, exhausted by the evening activity, he drives back to his apartment, which he and Mom had shared since they were married nine years ago.

For 18 months, now, Elmer has been making this trip to the nursing home, missing visits only when the roads are too bad for him to travel or his own health prevents him from going. When one of my brothers asked him to join our extended family for my nephew's wedding in Alabama this past weekend, he declined, saying that since Mom's condition prevented her from being at her grandson's wedding, he should stay with her, instead.

"One of the things this family has taught me is loyalty," Elmer, divorced twice before marrying my mother, said to my brother.

I thought about Elmer's words as our family gathered to celebrate the wedding of Timothy and Kimberly, ages 23 and 19 respectively, embarking on a commitment that will hopefully last a lifetime. With three more nephews marrying within the next year, weddings and marriage were much-discussed topics throughout the weekend.

"What makes a marriage last?" I asked my siblings - whose married lives add up to more than 270 years - as we sat around the breakfast table the Sunday morning after the wedding, reminiscing, missing Mom, and each of us probably recalling the early days of our own marriages.

Our family's marriages, like all marriages today, have been challenged - by job losses, unplanned pregnancies, cancer and other life-threatening diseases, alcohol and drug abuse, financial struggles, mental illnesses, raising children and step children, even stillborn births and the untimely death of a child. Yet somehow they prevailed.

Is it loyalty or perseverance, common values or commitment that make marriages last? There is no clear-cut explanation for successful marriages, we agreed, only the elusive emotion called love.

But there is nothing elusive about Elmer's nightly devotion to my mother during her final stage of life. If he learned loyalty, as he said he did, from watching our family prevail against the challenges of marriage, he certainly learned it well.

My wish for Timothy and Kimberly, as well as for the other soon-to-be newlyweds, is that they come to show the depth of their love, just as Elmer has.