For only children, friends are everything. When I was young, I wasn’t able to articulate this –I didn’t necessarily call my besties by the name of sister– but that’s what they were. Since we didn’t share a common blood line or a bathroom, these relationships took on a cordial quality that doesn’t exist between real sisters at that age. We didn’t fight over clothes or privileges but instead spent our hours collaboratively at play, which translates in the present day to meeting for cocktails or getting our nails done.

Our play dates were all shades of pleasant, long enough for satisfying exchanges without getting on each other’s nerves. Sleepovers, which involved bending the rules for pillow forts and living room camp-outs, were special enough to merit our best behavior to ensure they happened again. Even today when my girlfriends stay over, the occurrence is so few and far between that we create only the best of times, seeding our relationship with candy-colored memories. Rarely do we feud, and so, my closest friendships have a certain sweet politeness that isn’t necessarily present in my romances or professional relationships.

In primary school, my BFF was Jennifer. Our friendship sparked in an era when the most popular girls shared her name, but she was different from the others in our class. One year, there were four in room of thirty, but my Jennifer had a certain je ne sais quois. Like me, she loved mysteries and science rather than dolls like most other girls. (A candidate for social services, my orphaned Barbie was poorly clothed and lived a neglected life in a dark, tattered box.)

During our six years together, Jennifer and I invented board games that involved derring-do and unfortunate endings for our hapless cast of players who often fell into spiked pits or had their heads removed by guillotines. We snuck around on elbows and bellies during reconnaissance missions, attempting to spy on our parents and report back the secrets we learned. We created greeting cards for sale under the imprint The Cuckoo Company, peddling our wares door-to-door to neighbors. We both played the flute and were in the SAGE program for accelerated studies, which meant that we researched subjects like marine biology or paleontology rather than taking regular lessons a few times a week. My parents dubbed us The Bobbsey Twins because we spent so much time together; the irony is that we couldn’t have looked more different, as Jennifer was Chinese.

To me, such things mattered little. Like accepting any customs from another family, the traditions of her house were equally foreign, except for one: we both had grumpy fathers. Neither Mr. Lin nor my father liked noise, so we spent much of our time attempting to restrain our spirited play, finding ourselves constantly shushed no matter whose house we were in. Mr. Lin smoked Winstons whereas my dad smoked Camels, however Jennifer didn’t develop the same asthma I did.

When Mr. Lin was out of town on business, Jennifer’s mother, Grace, whose Chinese name was Minghao, would call my mother for American recipes. If I came over during these times, I’d find my mother’s pasta sauce or Steak Diane on their plastic orange plates instead of stir fry. Mr. Lin forbade Grace from cooking anything other than traditional Chinese fare when he was home. I always wondered if he could detect the underlying aroma of beef stroganoff when he returned, or if the spicy smell of Mrs. Lin’s kitchen covered over any trace of my mom’s buttery influence.

Jennifer had an older brother, but for as much as he ignored her, she might have been an only child like me. We were thick as thieves until junior high; even at that age, the irony wasn’t lost on me that she ended up becoming best friends with another girl named Jennifer. Both of their parents had more money than mine –Mr. Lin worked for IBM– so it made sense that their friendship should blossom at a time when it was important for girls to have things like Guess jeans, gymnastic lessons and family vacations, all of which my parents could only spottily provide.

At the time, I felt betrayed, watching us grow apart bit by bit as the Jennifers went to concerts or the mall. If Jennifer were my real sister, I probably would have yelled at her, but without siblings to practice on, I didn’t know how to do such a thing. I soon made new friends, many of whom lasted through high school and a few into college, two in particular, who helped me get into more trouble than I could have found alone. These relationships were more mercurial and eventually fizzled in adulthood.

There is a season for everything, especially love and friendship. Our relationships begin from shared experiences –we are attracted to people who are like us in some aspect– but as I grow older I am beginning to understand the ebb and flow inherently within. We are growing and changing all the time at different speeds, which affects how compatible those shared experiences remain to be. Add the dynamics of marriage, children, jobs and relocation, and the possibility of sustaining these friendships remains much more precarious without intentional work.

This past week, two of my besties announced they are leaving Seattle in December. These exits seem to happen in clusters, as it was the fall of 2010 when both Brad and Laura departed, one for Bogotá and the other for Buffalo; two years later, it was Jessica and Aaron. I saw Kim yesterday for the last time before she leaves for her family home in Ohio. For years, our bonding ritual has involved pedicures at Frenchy’s Day Spa, which I have done alone on occasion. It’s never as fun as when we’re together.

Kim was a candidate for friendship from the start. We’re both from the Midwest and we’re survivors of employment at Skyway Luggage (and survivors in general.) Not since Jennifer have I had such giggle-fests, the kind that cause the well-coiffed ladies in Frenchy’s to give us piercing looks over their bifocals. In addition to a tiara collection and a powerhouse craft practice, Kim also has a big heart. I have friends who give me tough love, which I appreciate from time to time, but when I need someone to share my internal messiness with, someone who doesn’t carry the threat of an existential kick to the side of the head, she is always there. More often than not, she has been there herself.

In spite of its inherent challenges, I believe that our friendship will survive the coming distance, like my ties to Jess and Aaron, Laura and Brad. We don’t talk every day, in fact, months pass without a real conversation, but when we do talk, my faith is renewed. We are still growing and changing, becoming more interesting as we push ourselves into new territory. It’s like reuniting with a college sweetheart after years apart only to find that their experiences have leveraged the things that you loved about them into something even better. Their achievements make you proud and make you consider the state of your own life; their courage helps you become more courageous yourself.

This isn’t always so, of course. Sometimes, there’s just evolution and the weaker offshoots die. People move, or just move on. They grow apart and that’s that. Jennifer and Jennifer didn’t last long; I don’t know who she ended up becoming besties with in high school. We were so socially distant by then that she didn’t even come to my mother’s funeral junior year.

Expectations change, too. If I get a text or Facebook tag from my far-flung friends, it’s as welcome as a phone call or letter. We’re thinking about each other, and it’s enough. Little nudges can actually have a great impact on friendships that span thousands of miles. In the advent of mobile communication, the interwebs are actually promoting connectivity just as their proponents promised long ago during the days when email was considered a cop-out.

At some point, even in the best relationships, we stop becoming obvious to each other with distance. Once removed, our friends pass out of daily thought and routine; new people fill their places, but it can take a long time. It’s harder to find and maintain true friendships in mid-life, so we do it cautiously. I find this especially true for those of us who don’t speak the lingua franca of offspring, making our truly deep friendships that much more important and rare.

The desire for connection is something we downplay at a time when most forty-something professionals walk around with No Vacancy signs around their necks. Spouses, children and couples dinners fill our dance cards, driving those with openings for new relationships to better themselves through group activities like pottery workshops and exercise classes. Yet, if well tended, these branching off points make new opportunities for growth in our personal networks, including travel adventures that might not otherwise have happened. (Bogotá, here I come!)

In eighth grade, my new best friend, Christal, moved back to Georgia. We cried when she left, wrote frequent letters, talked for hundreds of hours on the phone, then lost touch after a year. Deep down, I knew that her leaving meant that we wouldn’t see each other again. Yesterday, as Kim and I hugged goodbye in the parking lot, I was sad but not afraid, feeling hopefulness for her future and resolve for ours. Certain relationships are stronger, the connection deeper than most; given changing conditions, they may wane in intensity but not break.

I was surprised, pleasantly so, when Kim took my hand as we sat in the big puffy leather chairs having our feet massaged. It’s rare to have a grown-up friend who wants to hold your hand in public. We sat there squeezing palms for several minutes, sharing a silent prayer that she can weather all the changes of the coming weeks and months and a promise to stay connected despite the miles.

On my way home, I felt bad for not crying when we parted, but I realized that I don’t consider Kim’s move as the end of our friendship, like I did with Christal or Jennifer. It’s the next chapter, yes, but not the conclusion. We’ll stay in touch through technology and sometime in future, we’ll see each other again. When we do, we’ll feel proud of what the other has accomplished during our time apart.

That’s the thing about having sisters, I’ve discovered; you don’t have to say something to be understood.