Cutting contact with her best friend of 12 years was more painful than any romantic break-up Keeshia Pettit has experienced.
"She was this person that I felt very safe around, very comfortable with and I could be myself," says the 31-year-old podcast producer from Sydney/Gadigal Country.
"[We were] two peas in a pod. We used to hear it all the time.
Keeshia broke up with her bestie seven years ago, and says she still feels sad about it.
"She started doing some things that I just really didn't agree with … I found out that she'd lied to me.
"There was a fracture that occurred in the friendship, and I didn't ever see it going back to how it used to be."
"[After the break-up] I'd lost this really, really important person in my life that I'd envisioned this future with."
Clinical psychologist Hannah Korrel has written a book on friendship break-ups, and says every person she's spoken to has gone through some kind of relationship breakdown with a friend.
And yet, there isn't much research on how we interact in friendships.
"[It] doesn't matter what your age is, everybody's gone through it. So I think it's a massive blind spot in society that we probably need to talk about more," Dr Korrel says.
ABC podcast Ladies, We Need to Talk did just that, looking at the heartache of friendship break-ups — and why we're often at a loss when it comes to dealing with them.
The value of a bestie
Female friendships are often based on talking, interacting and intimacy, explains Dr Korrel, unlike men, who focus on "physical proximity and doing a task".
Dr Korrel says women might feel as if they have found a "kindred spirit" in another woman who feels like a sister.
For Keeshia, her bestie was her chosen family.
"We were the type of friends that would spend all our family vacations together, but also really big moments … even Christmas.
"She was the first person I always wanted to talk to. We always knew what each other were up to."
There's a good reason friendship can feel so safe and special, says Dr Korrel.
"A good friend is associated with turning off your sympathetic nervous system, and turning on your parasympathetic nervous system, which is the one that's called your rest and restore system."
Basically, besties can help us switch off our fight or flight and feel calm.
The difficulty and pain of conflict in our friendships
Melanie, who asked we don't use her real name, met her best friend in her fourth year of uni.
The Canadian says as roommates, they had the "perfect partnership".
"She did all the cooking and I did all the cleaning — we kind of saw the world the same way," the 33-year-old says.
"We played a lot of dance on the [Nintendo] Wii and watched dumb reality television."
Once their study was over, the pair were living hours apart, but were in regular contact.
That was until Melanie says her friend became pregnant and began reaching out less.
A miscommunication about what they needed from each other at that time ultimately led to a breakdown in the relationship.
Melanie says she knew the friendship had taken a real blow when her friend posted pictures of a baby shower Melanie was not invited to.
"It's more complicated when you don't live close … in the sense that it's harder to reconnect because you're not running in the same circles," Melanie says.
"You're not going to be seeing the same people. There won't be those organic opportunities to mend your friendship."
When a friendship is in trouble, many of us don't have the tools to help it get back on track, Dr Korrel says.
"We don't teach people how to deal with conflict … or learn how to speak your boundaries.
"Especially women, we're supposed to be, 'don't rock the boat' or be easygoing."
She says a lot of people find addressing issues in friendships confronting and awkward, so they just… don't.
And when a friendship comes to an end, the heartache can be as crushing as the end of a romantic relationship.
"[There is] this chemical reaction in your body [that] actually hurts … it hurts your muscles, it makes you feel heavy, physically heavy," Dr Korrel says.
Having never experienced a romantic break-up (Melanie is married to her university sweetheart), she says it's been particularly hurtful.
"I have a much better understanding now of what heartbreak can feel like and how you're just looking for that closure and thinking about what you could have done differently.
"I miss her."
What 'could have been'
Keeshia recently saw a post on social media of her friend getting married.
"She looked so beautiful, and she looked so happy, and I didn't have any idea that this was going on in her life."
Keeshia says she is "seesawing" over whether she should reach out.
"I don't know how each of us would feel in terms of being defensive over why the relationship ended, or whether she felt as hurt as I did, or whether she blames me for ending that friendship.
"And I would want to think now that I [give] people more grace and a bit more of an understanding and empathy, because I've been afforded those graces as well."
Keeshia says it makes her emotional thinking about what the friendship could have been.
"If you're lucky enough to have a friendship, that feels so easy like ours did … they can be like a persistent love that you have throughout the rest of your life.
"I feel sad talking about it because I feel as though … it could have been something that we took to our graves."