Two days before I left South Dakota, Rex and I sat talking beneath the open hatchback of my car. In the distance, a lightning storm moved toward us over the open expanse of the Great Plains, churning the sky a murky purple.

He was talking passionately about lithium batteries.

The more he talked, the less he and I seemed to have in common. I considered myself someone who could become interested in almost anything, especially when I was attracted to the person speaking. But now I asked myself: Did I care about batteries?

He and I were volunteers on the Pine Ridge Reservation, building and repairing infrastructure. He had been the first person to greet me when I arrived at the end of the long, dirt road. When he climbed out of the cab of a skid loader, and I saw his face, my body warmed.

In the lyrical version of what happened as the storm approached, we would have stopped talking and taken seriously the pleasure of our bodies. But wanting to have a baby had made dating in my late 30s less like a poem and more like a math problem. There was a lot that had to line up, and what I was looking for now differed from what my younger self had envisioned.

I didn’t care about dating someone for a certain amount of time before we had a baby, or being in love, or getting married. I wanted to like the biological father of my child, maybe admire him. That was about it. I had arrived at this set of criteria because the alternatives seemed sentimental and unrealistic, especially the husband-to-be wish lists that many of us champion during those years when we are both ready and able to have children.

With the help of my sitting meditation practice, I had observed that the more I worried about getting pregnant, the less discerning I was about love, an effect I feared would intensify as I got older. How could I trust my judgment under pressure? Wouldn’t a lot of men start to smell like fathers?

I decided the safest way to protect myself against romantic delusion would be to separate the two stories from the outset: I could try to find a mate or become a mother, but not at the same time. Since biological constraints made it easy to figure out which was more urgent, I resolved to have a child outside of the context of love.

My solo road trip to South Dakota was conceived as an experience my future self, the one saddled with a dependent, would someday thank me for. When I returned home, I planned to get pregnant using an anonymous donor’s sperm.

On my last evening with Rex, kissing in his tent, I realized there was a lot about him I didn’t know — who was in his life, where he worked, his last name.

Before I crawled out of his tent, he asked for my phone number. He was headed home to Michigan, and I to California. I told him I thought we should leave things exactly as they were, which seemed perfect to me.

“What, are you crazy?” he said, and he gave me his number.

Back home, I pored over donor questionnaires at the local sperm bank, trying to keep straight who liked video games and who preferred billiards, but it all mixed blandly together for me.

Phone conversations with Rex, though, were weird and memorable. He had inherited his father’s expressions such as “Son of a biscuit!” and “Jeez O’Pete’s!” Doting on his backyard laying hens, he often referred to himself as a “chicken mama.” He was the only 30-something adult I knew who had traveled on an airplane exactly once, a domestic round trip for a former job.

We didn’t talk much about the parts of our lives that existed beyond the present. He mentioned that his relationship with a woman in Michigan was crumbling. All he knew of my path to motherhood was that I wanted a child.

When my search for a donor stagnated from lacking a warm feeling about any of them, friends offered to screen profiles with me on the eve of my 40th birthday. Two donors received my friends’ approval, so I put myself on the wait-list for their sperm, though I still felt ambivalent.

When I finally told Rex about my stalled plan to become a mother, he said, “I can help you with that.”

I was silent. Then I said, “Don’t say something like that without thinking about it.”

“I have.”

He wasn’t interested in being a father or co-parent, so the scenarios we discussed assumed that by the time I gave birth, he and I no longer would be romantically involved.

Soon he visited me in California and had his first experience soaking naked with strangers in hot springs, his first contact with thousand-year-old redwood trees (he cried). He gave back rubs that were accurate, not clumsy; his hands were full of life. We were still working on our donor arrangement. We were also falling in love.

I went to stay with him in Michigan, where he taught me how to use a chain saw and care for chickens. Eventually, he followed me back to California, driving the whole way towing a homemade trailer filled with tools.

During this time, we were trying to live two separate stories: the one in which every month we tried to conceive, and the other in which we were still getting to know each other. But the more we enjoyed ourselves, the more confusing our situation became. If I got pregnant, would he leave the relationship? If I didn’t get pregnant, would I switch to another donor?

About a year after he offered to be my donor, we began to have these difficult conversations. And in the middle of them, I got pregnant.

Such was his generosity that he was genuinely thrilled for me. Inwardly, though, he began to withdraw. He still didn’t want to be a father or co-parent; the thought of either brought up old wounds from his childhood. Every day of his indecision, I was tempted to try to convince him to stay. Most days, I had enough sanity to recognize that doing this would harm us both.

On the day he left California, he took a photograph of me looking haunted. Then he got in his car and drove east. It was Father’s Day.

After he left, I scrambled into action, interviewing midwives, searching online for used baby gear, and trying to explain to the being in my womb why I was crying a lot: “I’m sorry, baby. I’m OK, just sad.”

Then weeks later, without warning, a text arrived: “I made a terrible mistake.”

By then, I recognized he wasn’t the only one.

When love and a baby coincided for me, I still believed I could separate the two and remain fundamentally unchanged. Not until Rex and I were suffering was I able to see that the clean reality I envisioned had never existed between us. It had evaporated the moment he greeted me at the end of the dirt road, and my body responded with warmth.

Buddhism is founded on the truth that suffering is caused by desire, which at first glance can make both suffering and desire sound unequivocally bad. But the beauty of suffering is that it offers the opportunity to have a curious and tender relationship with desire, to listen to it rather than try to eradicate it. Often what I hear beneath my desire’s surface noise isn’t problematic, only human: the vulnerability in having a life tangled up with others.

In Rex’s absence, I remembered that tending to a lover or child is dirty work, in the most wholesome sense. We don’t fall in love or have a baby to have our points of view and preferences affirmed. We do it, at least a little bit, to soften our singular, lonesome grip on reality and invite in the unexpected, the undesirable and the inexplicable.

This — call it messiness, or richness, or hands full of life — is what is beautiful and natural about being an animal with appetites beyond our understanding. Being faithful in the deepest sense to a lover or baby is saying yes to the weird and memorable before you know you want it or welcome it.

Rex came to this in his own way. He told me that since he left California, he had been listening to podcasts about fatherhood and looking at the photo of me he took the day he left. He’d been crying, too. And he wanted to come back.

“To the baby?” I said. “Or to me?”

“Both,” he said.

And he did. He sold his heaviest tools, repainted walls and put his house in Michigan up for sale. And two months later, he was back in California in time to catch in his hands our son being born.

Katharine Dion, who lives in Emeryville, Calif., is a mindfulness-based life coach and the author of the novel “The Dependents.”

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