For every single one of us, there will be a goodbye that defines us.

It may be filled with tears, or with none. We may blubber messily or muddle mutely through the heartache. We may emerge resolute in our conviction that this is just a bridge, and that we'll say hello one day again, or we may dissolve into tears at the thought of never capturing the moment again.

For each and every one of us expat girls, there will be that Judy Blume summer that immortalises our childhood.

For three weeks, I've been watching my 12-year-old and her best friend recapture three years of lost time. They're expat girls, a little spoiled, a little naive, a little privileged. They're expat girls, they've lost so many friends along the way; they've had to make so many new ones. They're expat girls ... they have that ONE friend that will forever remain etched in their heart. They're expat girls, they have that ONE friend that really GETS them, no matter where they may be, no matter when, no matter what. They're expat girls, they're not perfect, but they're resilient, and they're flipping-ass brilliant.

This summer was all about two expat girls getting to turn back the clock. They got to be 9 again when they felt like it. They played with Barbies again, with no concern about the popular girls teasing them. They watched Disney movies and Horrible Histories, and didn't worry a single moment about anyone thinking that was odd.

They watched Pretty Little Liars like 14-year-olds, and I acted like I had no idea they were watching. They tuned in to Netflix to watch a series on eating disorders amongst teens. Then they flicked on YouTube to see what Miranda Sings and My Little Pony were up to. (I don't ''get'' Miranda Sings, ... then again I was watching the ''Rocky Horror Picture Show'' with my best expat friend Lisa Miller and sneaking in ''The Blue Lagoon'' when I was 12, and I'm pretty sure my parents wouldn't have gotten that either had they known we were watching it).

The point is they got to be whatever age they wanted for a whole three weeks, and they owned that power to the fullest.

They challenged themselves physically and mentally, crossing gorges, zip-lining across ravines, rappelling down cliff sides and hiking up mountains.

The next morning, they slept in until 11:00.

They went out and had raclette and fondue on their own. They enjoyed campsite BBQ's and lakeside picnics. They ate ice cream. They played UNO. They helped me make puzzles. They walked through cow pastures and petted wild mountain goats. They swam in lakes and rode on roller coasters. They swung on swings and slid down slides.

They talked about boys. They talked about girls. They commiserated about their shared fears of returning to school, about the nightmare of Grade 7, about the horror of homework. Sometimes they didn't talk about anything; they just hung out. Sometimes they hung apart.

This was definitely their summer to remember.

I got to watch them plot, and play and commiserate, and worry, and laugh and dance. I got to hear them giggle, and argue, and blabber and sing.

And tomorrow, I'll watch them say goodbye. A goodbye that is sure to rock their world.

I don't think they'll necessarily know why. I think they might not quite realise that they'll probably never play Barbies together again. They may not grasp that they'll probably never recapture the wonder of pretending you're 9 or 14 when you're actually 12. They probably don't understand that some summers, some moments, are made for remembering, but can never be revisited.

I think they'll look back on this summer many years from now and smile. I think they'll carry this summer within them for life. I think they'll remember the goodbye, but mostly I think they'll remember the moments before the goodbye.

The moment when they fell into each other's arms at the airport.