A couple of nights before my recent birthday, I momentarily slipped into an expat funk.

The boyfriend was going to be away for work the night before, so I wouldn’t have anyone with me when I woke up. My parents wouldn’t be there. And while I had planned a joint birthday bash for the evening - well, what if nobody came? “I wish I was back home in Australia,” I whined. “Then it would be a real birthday.”*

(No, I was not turning 11. Although that would be an easy error to make based on the above paragraph.)

Of course, if I had been back in Australia, it’s not like I would have experienced some fairytale birthday surrounded by all my closest friends and family, either. Because even though I only left Sydney nine months ago, it is already no longer to Sydney I left. Landslide change in state government aside, people have left as others have returned. It’s the way it has always been throughout my adult life - a constant ebb and flow of people and places - and it’s the reason I decided to write my cover story for last weekend’s Sunday Life; on travel, transience and friendship.

The story has obvious links to my current life as an expat in London, but it’s an issue I’ve been thinking about since long before I left. Travel has been an unavoidable factor in my social life for years - if I haven’t been doing it myself, plenty of people I love have. When I’ve been the one to pack my bags, travel has always seemed a great (if somewhat bittersweet) adventure; when it’s been my friends jetting off for a year or five, it’s been the unwilling extraction of someone I care for from my life.

It always struck me as being a bit at odds with our current elevation of friendship. On the one hand, friends are “the new family”; vital bonds of utmost importance to us. On the other hand, many people I know are highly mobile, and don’t hesitate to leave behind either friends or family to go on their next adventure. In some ways, it’s a tug-of-war between community and self: you want to get to know people and places well enough to love, connect and commit to them; but on the other hand… there’s a big, wide world out there.

I wonder if I’ve been thinking about it all wrong, though. Since moving to London last year, I’ve had enough friends stay at my house that I’d probably need to use both hands to count them. Transience doesn’t need to destroy our bonds with each other; it can equally be used to enhance and redefine them. For example, on the morning of my birthday, one of my good friends flew into London from Melbourne. He was in town for a conference, and had only booked his ticket 48 hours beforehand. That night, two of the boyfriend’s best friends flew in from Sweden; they were spending the weekend England for another friend’s birthday.

I’m not saying such incidents approximate the enmeshment in one another’s lives we see in TV shows like Sex & The City or Friends, but they are a nice way to connect, and arguably better than the once-a-month coffees or breakfasts most of us manage when we actually live in the same cities. They also speak of a certain level of privilege: living in London, I have become aware that even comparatively “cheap travel” is still pretty damn expensive.

So to answer Shitika’s question, I don’t spend a whole lot of time worrying that someday, if and when I return to Sydney, it will have moved on without me. Because even if I’d stayed put, the people around me wouldn’t have. I’d be staying put alone. I do worry sometimes about how our relationships will withstand all that time and distance, but distance can be created by more than just an absence of physical proximity, and we’ve a long, change-ladden road - and hopefully plenty more birthdays - ahead of us.

Related: Ask Rachel: Do you ever want to pack your bags and go home?