The following is a guest post from Barry Petersen, Emmy Award-winning CBS News correspondent and author of “Jan’s Story: Love Lost to the Long Goodbye of Alzheimer’s”

When does a marriage die even if the love never does?

We are not talking about the kind of rifts that can lead to divorce. We are talking about when someone fades and disappears so far away mentally, that there is no longer a relationship.

A hypothetical question? Not in my life, and very soon…not in the lives of millions of unprepared Americans. As Baby Boomers age, more and more couples will face this…one with a mind diminished and slowly being erased, the other healthy and vibrant. There will be many travelers on this journey.

The reason is Alzheimer’s Disease. I first heard those words in 2005 when my wife, Jan, was diagnosed with Early Onset Alzheimer’s. She was 55. At first, I cared for her by myself. I am a CBS News Correspondent and at that point we were based in both Tokyo and Beijing, traveling between the two cities. Then, as Jan worsened and because of my need to travel for my job, I hired a live-in caregiver, a retired nurse from Tacoma, WA.

Finally, in May, 2008, I made the decision that ended our shared life as we knew it; I placed Jan into an assisted living facility in the United States. I kept living in Asia, continuing to work, and each time I went back to the US and visited her, I could mark the changes as she spiraled downward.

I learned to accept that she no longer knew me when I came to visit. The Barry she remembered is someone deep in her past, not the man in front of her today. There were tears about this, but always in private, never in front of her. She would not have understood, and that would have frightened her.

Yet it ripped at my soul. This woman I had wooed and won, who had shared adventures living in Asia and London and Moscow, who had once been a successful foreign correspondent in her own right, had gone away.

People who know us would use one word to describe us: “BarryandJan,” because we so loved being together. Now, she was adrift somewhere else, and the Alzheimer’s meant she could not tell me where she was, or why, or what it was like there.

And there was guilt. Who cannot weep when the one you love disappears, who cannot feel the rage I felt, asking myself: “Why her. Why not me?” Jan was the better person of us as a couple, the bright star in whose glow I happily lived. She was the good of us. Who had the right to take that away.

And in time there came the hardest question of them all: Is it still a marriage if only one person is mentally present?

In that answer lies the future…to spend the rest of my life alone, even though Jan had gone away? Or – decide that I needed to go on with life.

To move on was to tempt the rage of those who told me I was violating my wedding vows. Their morality was clear – the vows say ‘till death do us part,’ and that is what people have forever promised.

Except now, people live longer, and that means Alzheimer’s comes more often because the major risk factor is simply … growing old. One in eight people over 65 have Alzheimer’s. Almost one in two will have it by age 85, according to Alzheimer’s Association. And 85 isn’t that old anymore.

There were others who told me it was time to accept that my relationship, and with it my marriage, had changed and that I was alone. I was surprised at some who said it. A couple I know who have been married, happily, for decades – people I thought would be strongly pro-marriage at all costs and would tell me never to break those vows – were among the first and most adamant to say: find someone to be with, create a new life, do not surrender to loneliness, do not fold up, dry out, and die.

Dying was an option. I thought about it, faced with the sense that I had lost the one reason for getting up and going to work and enduring Shakespeare’s “slings and arrows of outrageous fortune.” My fortune was dark and doomed, or so it seemed.

It was time to make a call. I could not keep going on as I was, finding solitary friendship in ever more late night alcohol.

I reached out, not well at first, after a friend signed me up for an internet dating site. I set one rule – that I was honest about still caring for Jan, yet willing to explain that the marriage, the relationship, were victims of Alzheimer’s. The marriage, as I defined it, was gone. Finished. But if someone could understand and accept that, they also had to understand that Jan was still with us, still alive, and I was still her husband and the man who was watching over her. Jan and my care for here was a part of the package.

There were women who instantly rejected me for this, and I understood. There were others who wanted to move quickly into a relationship, and that I also understood…and rejected. Frankly, they scared me off.

In time, and with time, there was one. Mary Nell is a widow, wise in the ways of grief, who understood the being alone part far better than I, and accepted that this would be an unusual pairing because we would not be two, but three. Our relationship would include Jan.

And so it does. Mary Nell and I go together to visit. Jan can’t remember her name, but remembers that Mary Nell is a friend and throws her hands open for a big hug and hello. Even though we are together, Jan sees no connection between Mary Nell and me. And Mary Nell sees Jan as a friend, someone she now cares and worries about. It is more often Mary Nell who says…we need to bring flowers, we need to get her new shoes, or she’s out of her favorite lipstick.

The moment we leave, Jan forgets that we were ever there. She forgets the flowers we bring, or the songs we sang together as I played the piano for her.

Mary Nell and I call ourselves the “New American Family,” and perhaps we are a Marriage of Three. We surely are the precursor of the tsunami of dementia and Alzheimer’s and difficult decisions to come. We will soon be joined by millions of “New American Families.”

I do not consider that comfort. I do not want anyone else to travel this dreaded path, but it is happening. Each diagnosis, and there is one every 70 seconds in this country, will bring others to this precipice.

I have no answers for others, offering only what I have done and learned and chosen, knowing that it was right…for me.

I wish them luck. Like me, they will need it.

About the Author: Barry Petersen is an Emmy Award-winning CBS News Correspondent who has reported on everything from wars and natural disasters to Paris fashions, Welsh choirs and the return of American Jazz to Shanghai, China. His stories have been datelined from virtually every continent in a career that spans more than three decades. Petersen wrote his first book, Jan’s Story: Love Lost to the Long Goodbye of Alzheimer’s published in June, 2010, about the struggle he shared with his wife, Jan Chorlton, who was diagnosed with Early Onset Alzheimer’s Disease at age 55 and is now in an assisted living facility. Jan was also a CBS News journalist, reporting from both Japan and the former Soviet Union for CBS Radio, CBS Sunday Morning and the CBS Weekend News. Petersen is currently based in Denver, CO, where he reports for the CBS Evening News with Katie Couric and CBS Sunday Morning with Charles Osgood. Visit www.barrypetersen.com.