Girl meets boy. Boy already has kids. So then what? Sarah Humphreys shares her story of nebulous identity, awkward assimilation, and true love.

Photo by Charlotte Jenks Lewis

The name tags are laid out for the parent-teacher meet-and-greet. My name isn't there. I Sharpie "Sarah Humphreys" on a blank one, but that doesn't clarify much, because I am actually the fiancée of the dad of a new student going into kindergarten. Which is as hard to jam into conversation as it is to fit on a tag.

I had spent nearly 37 years as a relatively single, relatively happy, hardworking New York City girl. I planned fun vacations, mastered needlepoint stitches beyond the basketweave, dated fruitlessly, strolled endlessly. Every Christmas I would carefully select a Fraser fir (no exceptions) to fit justright in my West Village one-bedroom, decorate it with a galaxy of white lights, and breathe it in. Over the years, I watched all my friends get married, then have children, and I was still sitting on the couch in my apartment, Kenny and Dolly singing "I'll Be Home With Bells On." Fundamentally I was sad—I wanted to be a wife and mother more than anything. But day to day, for what felt like forever, I focused hard on the things that were in my control and fulfilled me: job, friends, family. I was confident and secure in my cobble-stoned corner of the world.

And then I fell immediately, completely in love with a man named Ron—who also happened to be a father of two small children, a boy and a girl ages five and three. It was magical and miraculous that I met this guy, but what the what?! Think of a pneumatic tube: Whoosh! I was picked up and dropped in another life.

Now that I suddenly was this person, who exactly was I?

OBSERVER: Things felt so certain so quickly between Ron and me, but the surrounding situation was new and fragile. He had just separated from his wife before we met; he and the kids had only started to find their footing as a family of three. We didn't know when the time would be right for me to meet them—but it wasn't now. So I got to know them from a distance, mostly through a steady stream of photos and anecdotes. On the days Ron didn't have the kids, he and I carried on our mad love affair and began intertwining our livesmeeting each others' parents, sharing the occasional toothbrush. When he did have the kids, I was back on the couch in my apartment, lady in limbo. Every once in a while, on those days apart, Ron and I would be on the phone and in the background I would hear the kids' voices, so Minnie Mouse­ish and innocent. It made my heart heave—a strange combination of longing and contentment. My future was right there, on the other end of the line. And just knowing that was, right then, enough.

FAIRY: A few months into the Waiting Phase, I started flitting around behind the scenes. In retrospect, it must have been some reverse, blended-family version of nesting—prepping myself to become part of the household. I would go into Ron's apartment when the kids weren't there and leave homemade macaroni and cheese in the refrigerator, hang new dresses in the closet, act as divine messenger when school needed a turkey for the Thanksgiving feast. It was enough to lend a hand and feel part of things, but not enough to reveal my existence.

Ron and I continued our conversations about when and how to make introductions, and we were getting closer to the answers. But there were more questions out there, murky and slightly foreboding. How and where would I fit? What would the family dynamics be like? And—the one I belabored most—who would I be to them? Buddy? Too progressive. Mentor? Too stiff. Second mom? Too presumptuous, too dangerous.

"FRIEND": I met the kids on a cold Saturday morning in March, almost a year and a half after meeting Ron. We settled on a slow ramp-up plan. Overriding mantra: Don't eff this up. And the first encounter would be about my getting used to the kids before they had to get used to me. I posed as an innocuous friend of friends, tagging along on a multifamily ski weekend, and Ron and the kids picked me up to go to the mountain.

Let me just say: It is quite a unique thing to open the hatchback of a car to load in your skis and see your future step-children in their car seats, shiny-haired heads turned to check you out, a random woman along for the ride. You try to act casual and cheery, but your voice is shaky and your eyes are wet. You sit, twisted around in the passenger seat, and watch them chatter on about black diamonds and hockey stops, and the love you already had for them swells into something so solid and heart-bursting and overwhelming. You cannot quite believe that they are real, and this is real.

I spent the rest of that weekend watching and participating in a friend-of-a-friend way. And as I slowly spent more time with the kids and Ron over the coming months, just the four of us, questions of ownership started to arise. I was definitely Dad's friend—we had made that clear. But when an adult referred to me that way in front of Ron's daughter, her eyes got wide and she said, "Sarah's my friend, too." And then this happened, a couple of times: "Daddy, you're the best daddy in the world. Sarah, you're the best... adult friend in the world."

FLAILER: Oh my. When I, as a single, childless Christmas-tree perfecter, parachuted down into the family and started to occupy the space a mom type might—partaking in weeknight dinners and weekend trips and eventually moving in—there were so many things I didn't know. How much do the kids eat? How short can you cut their nails without it hurting? How bad does behavior have to be to lose five minutes of computer time? How do you contain all the loose things? (So many goddamn loose things, especially in the car, falling off my lap, makes me crazy.)

I bought tote bags to corral the crayons/clementines/spare sneakers, but I struggled to learn the rest, particularly when it came to discipline. We had some hard nights, me trying to stand my ground, unsure if I had ground to stand on, terrified that any misstep would confirm to the kids that I was, and always would be, a fraud. Parents earn their authority through years of being The Parent. Parachuters have to act like they have it (awkward) until they start to actually have it (still waiting).

ALMOST STEPMOM: Ron and I got engaged in April, on a family trip to Florida. When we shared our news with the kids, his daughter had lots of questions; his son agreeably grunted. And over the next few days they started trying out my soon-to-be title: "When you're my step-mom..." It felt nice to hear it, and to know that I would finally have a single, official word to identify me at parent-teacher gatherings and everywhere else.

But here's what I was already starting to realize (and now, just a month away from the wedding, I know for sure to be true): The person I've become has everything to do with who I was and what they need. I'll peel their clementines in one long peel because it's neater that way. I'll home-bake their birthday cakes, crumb coat and all. I'll pull the plug when their computer time is over and continue to work on my I Mean Business tone. He'll rest his head in my lap on the way home from Coney Island, and she'll ask to play our game of pretend every night before bed. And to them, and me, I'll just be Sarah.