Everything that comes with a relationship can be counted — in years, losses, gains, money, friends, family. The end of a marriage deserves an accounting. The numbers matter. We had been married 27 years. Two sons. Four houses. Thirty Christmases. The list does not have an end. Sometimes, emerging from a divorce, it takes a while for things to add up.

Three years ago, when I was 56, I suggested to my husband that he move out of our house in New Jersey. Our marriage had been faltering for years. As he was settling into his new apartment in Manhattan, he called. He was struggling. He said that he didn't want a divorce. He was sorry for his part in our breakup. It was October; he promised that we, and our two sons, would still spend that Christmas together as a family. We pledged that we would always be friends, and our family would survive. We would stay separated for a year and, somehow, together, figure out this whole thing.

Five months after our pledge, and six months into our separation, my husband called. It still wasn't unusual for him to call me. We spoke every few days. We even met for dinner or a drink on occasion. After a few minutes, as we were about to hang up, he told me that he was "seeing someone."

"Seeing someone." Two words that splintered my head into speechlessness, followed by a dizzying internal stream of, What about "Our family would survive"? What about "We'll always be friends"? What about "We'll get through this together"?

I sputtered into the phone:

"Who is she?"

"You're seeing someone?"

"Are we supposed to be dating?"

"What about me?"

"What about us?"

"How old is she?"

"Are you getting married?"

"What if she wants kids?"

"Who is she?"

My ex-husband is a business executive. He runs meetings. When I paused to catch my breath, he answered every question with purpose.

She was 39 or 40. (He was my age.) She was "very successful." He told me where she worked. He said he would always be in my life. "Nothing has changed."

He said he would never be with anyone "who didn't understand this."

And: "I told her I have two sons in their twenties, and I don't want any more kids."

Three months after that phone call, and nine months into what had become a separation that was now laying bricks on the road to divorce, it was time, according to friends and family, to "put yourself out there." "Maybe go online." "See someone!"

One girlfriend had started a profile for me on eHarmony. It took two weeks for me to bite — a solitary Friday night, over wine, when I was feeling especially feisty and brave. So I named myself Isabella on my eHarmony profile, put up a year-old headshot, and watched half in fascination, half in horror as eHarmony's computerized compatibility matrix churned out a slew of Santa Claus look-alikes — some on Harleys. (Not my type.) But eventually one stood out — a 59-year-old IT guy from Manhattan. We agreed to meet for dinner in my suburban town one July night. I wore my favorite black dress with the cool belt. It was my first date in over 30 years.

We sat at a table by the door, across from a misplaced water sculpture. We politely bantered back and forth about how each of us ended up middle-aged and single. We picked at tuna and scallops, washed down with wine for him and vodka for me. We talked about our jobs. He said this was his first date in a while. He told me he practiced Buddhism, and he said at a few points that I had good energy.

I wasn't feeling it. What I was feeling was tangled. Absurd. Inept. I didn't want to be there anymore.

While we were eating our way through 30 seconds of awkward nothing, I asked:

"So, you're holding a baby in one of your profile pictures. Is that a granddaughter?"

"No," he said. "I don't have any grandchildren. That's my niece's daughter."

He did have one daughter, he continued. She was 40. And she had no kids — was the kind who would hug them, and then be happy to give them back to their parents, he said.

"Wow," I said. "What's it like to have a child in her forties at 59?"

He said she was born when he was 19, and he was in and out of her life until she was older. Their relationship was less of a father and daughter, and more "an adult relationship." They were friends.

He tossed around some loving adjectives to describe her. She was "very successful." He told me where she worked. She was, he explained, dating an older man.

As my date continued to talk about his daughter, I half-listened. We really didn't have anything in common. He continued to tell me that, "about three or four years ago, when she was around 36 — she's 40 now, and will be 41 in December," she asked him how he would feel about her "dating a man who was almost his age."

I nodded, while swirling my scallop in sauce. I looked up. I didn't think much of what he was saying. Until he said, "He told her that he didn't want any more kids; he already had two sons in their twenties."

My brain clicked, my breath was stuck, and my stomach was walloped with a pang of odd familiarity. My head tilted. It took me a minute to find my voice.

"Is your daughter's name Michelle?" I asked him, fully expecting him to answer with, "No, it's Karen." Or Danielle. Or Tiffany.

"You know my daughter?" he asked.

My head shook sideways. My face crinkled. I lost my fork.

"Is her boyfriend's name Jim?"

His expression discombobulated into complete bewilderment. Not a word came out of his mouth. I came out of my body. The room became a blur of scurrying waiters, and all I could hear was the water recycling through its bad sculpture.

"I think... your daughter...is dating... my husband."

My head sunk. My hands were clenched.

"Your. Daughter. Is. Dating. My. Husband."

And then what he had said earlier hit me: His daughter came to him about the older man she was dating "about three or four years ago." Three or four years ago. My husband and I had separated less than one year ago. We were already a cliché. Now we were a soap opera.

I chugged my martini in record time. My date, who was not a drinker, more of a sipper, poured his wine to the back of his throat. I ordered another.

We finished dinner, stupefied; our heads shaking simultaneously. We were not sure where to take the conversation, beyond different ways of saying: "What are the chances?"

"In the millions," I thought.

We ended our date, said good-bye, and I drove home and sat outside on a concrete step just beyond my back door until the sun came up. My body was frozen in place; my mind was reeling round and round over my whole life. About how the undoing of my marriage, and the cracks, came early on. That we were a couple that friends often called mismatched — the whole "opposites attract" thing; we often battled — and how my husband and I had been on a long, circuitous sleepwalk to somewhat separate lives for decades. Our disagreements, or arguments, were emotionally brutal — I was usually a devastated, dilapidated, wet mess; he was always resigned. We often threatened to end it, but we were all words, no action. Since separating, we still had to figure out how to untie an old familiar knot.