Kalli* and Rebecca shared a lifetime of experiences. Friends since high school, they had seen each other through transitions and trauma, celebration and secrets. They had spent summers travelling together, marched in each other’s weddings, and been among the first to hold each other’s new babies. And then, after nearly 20 years of friendship, it was over.

Kalli’s father passed away unexpectedly in January of 2009, and though she relied on her family immensely, she was looking for comfort from the friend that had known her dad the longest. And she just didn’t find it.

The 37-year old mother of two explains, “Rebecca just couldn’t be there for me. And it was a pattern that was always there, but I couldn’t ignore it any more. My dad’s death was the thing that really opened my eyes, but I guess the cracks were always there. I know that as I got older, had a family, and saw a shift in my priorities, I had less and less tolerance for behaviour I could ignore or forgive before.”

“We talked about it, but it didn’t make anything better. So I just started allowing more and more time to pass in between phone calls. Eventually, I realized that it had been a year since we had talked.”

There is a misconception that, once we enter adulthood, life stabilizes. We’ve made it through the tumultuous years, the experimental years, the emotional years intact, and our reward is security and calm. Sure we expect some things to change and some people to come and go, but BFFs? No. BFFs are supposed to be solid, firm. They’re not supposed to go anywhere. There’s a reason that last F is there.

But, as Kalli stated, adulthood also gives us a greater sense of what our priorities are, and though the emotional need for our friend might be great, an unwillingness to spend precious time and energy on somebody that doesn’t seem to give anything in return, can be greater.

And even when the end of a friendship is something we facilitate, it’s not easy.

“I definitely grieved,” says Nancy, 41, whose 5-year friendship with a former coworker ended in, “a spectacular explosion of hurt feelings and things we probably both wish we hadn’t said.”

“For months afterwards, the reality that we weren’t going to be friends any more would hit me in the gut. There were lots of tears and lots of sleepless nights.”

The expulsion of someone from your adult life is tricky. Unlike in high school, when we may have opted for high-drama and a healthy dose of gossip to make it through the end of a friendship, adult friendships (much like a divorce) can carry a lot of baggage. Husbands and mutual friends are often caught in the middle, and when children are involved, things can become even more complicated.

“When I ended my friendship with Rebecca, I pretty much ended our daughter’s friendship with her daughter as well, “ remembers Kalli. Their husband’s did their best to arrange and shuttle the kids to playdates, but it was soon obvious that the situation was simply too awkward to continue. Too young to keep in touch on their own, the girls’ relationship became another casualty of their mothers’ break up.

Nancy’s friend didn’t have any children, but her own, now ages 4 and 7, continue to ask about the woman that used to come over with treats and plenty of attention for them. “It breaks my heart,” she says, “to have to tell them that somebody they were so fond of isn’t coming back.”

It’s difficult to edit somebody completely out of your life. Surreal as it is to ‘unfriend’ somebody you once loved from Facebook or Twitter so that you are no longer a part of their present or future life (and vice versa), it’s fully impossible to erase them from your past. Often, our biggest milestones and proudest moments included our BFF, and reminders that were once sweet can now be sullied. Wedding albums, baby books, vacation photos – these can seem ruined by the inclusion of somebody we no longer care for.

And with the loss of a friend comes the loss of all the little things that made the friendship important as well. You may have just broken up with the one person who understood intimately why your office is more bizarre than Dunder-Mifflin, or why you’ll never eat falafel again after a bad experience in Morocco 15 years ago. There might be nobody else that knows the punch line to a thousand little inside jokes, and that can be the hardest part to come to terms with.

“I’m almost 40 years old now,” says Kalli, “and it’ll be years and years before I can once again say that I’ve been friends with somebody for as long as I was friends with Rebecca. That’s tough.” But she does hope that the time will indeed come. “ I definitely don’t want to go through this again,” she adds. “It sucked when I was a kid, and it sucks even more now.”

We may no longer deal with it by scrawling long, tragic entries into our journal, or arranging mean-girl style coups against the ousted in our posse, but one thing, regardless of how mature or experienced we become, remains certain:

Breaking up is still hard to do.

*All names have been changed.