The three words that explain all your friendship issues.

Female friendships are some of the best and strongest you'll have in your life. They can be intense, so much so that, when they end, it can feel worse than a break-up.

The golden age of having a BFF for most people is when you're young. You can spend all of your time together because of shared spaces and routines, and you don't have other priorities (like your own family).

And then, you grow up.

Watch: This Glorious Mess podcast hosts talk about the different types of friendships. Post continues below.

People work different jobs, find partners or get married, move to different cities, have kids — life comes at you so fast and suddenly you never even see your friends or use the term "best friend" at all. Isn't that so high school? Or is that what we tell ourselves to make peace with the fact that having close, meaningful and supportive friendships feels harder when you're older?

Danielle Bayard Jackson is the Director of the Women's Relational Health Institute and the author of Fighting For Our Friendships, so she is the expert on female friendship.

In her appearance on Mel Robbin's podcast, she revealed the real reasons female friendships can feel so complicated — and how to rebuild them so you have the friendship group you need in your life.

Is making friends really harder when you're older?

Danielle Bayard Jackson might be a friendship coach now, but she actually started off as a high school English teacher — which was the perfect playground to observe how girls made (and lost) friends.

"I had 10th and 12th graders who I was teaching and I noticed that between classes and after school the number one thing the girls wanted to talk to me about was friendship stuff," she told Mel Robbins.

"I didn't realise that at the time, I was unofficially coaching them through their weird, awkward friendship drama and so the classroom was the first place where I saw how issues of connection and belonging directly impact everything else."

However, when Bayard Jackson moved into the media industry, she was surprised to find that these issues weren't specific to teenagers.

"I got into the world of public relations and I always joke that I made the foolish mistake of thinking I'm leaving that teenage drama behind because I'm working with adult women," she recalled.

"It wasn't long before I realised that despite the fact these women were charismatic, high-achieving extroverts — they, too, were secretly dealing with friendship stuff and so I just thought wow, at every stage of womanhood we're trying to figure out 'how do I better relate to the women around me.'"

Bayard Jackson said it's "not an age thing", and that it actually doesn't matter what your "background or generation is" — friendship issues are the great equaliser that everyone suffers from. Which might sound scary, but in a way, it's reassuring — you're not alone, and it's not just you.

The three words that will explain all your friendship issues.

In Bayard Jackson's book Fighting For Our Friendships, she suggests there's a framework of three "affinities" that are necessary for a positive female friendship — and the absence of any one of them is what can lead to tension and conflict.

The three traits are symmetry, support and secrecy.

"I started to notice that it didn't matter which discipline I was looking at — anthropology, sociology, psychology — I kept seeing these themes emerge… in terms of what women highly prioritise in their friendships and what makes them close," she said.

Symmetry.

Symmetry refers to how even a friendship is — how much effort two women put into their friendship, or how much they take versus give.

"Women really value these feelings of sameness and balance and reciprocity and egalitarianism," Bayard Jackson explained.

"Even if you go to a bar and you see women talking, you're overhearing them say 'me too', 'oh my god same', 'me too' — so, thriving on that 'I am you, you are me.'"

When this symmetry falters, Bayard Jackson said it can leave women feeling like they're moving in different lanes, or have some kind of irreconcilable difference.

The example she gave was when we judge our friends' careers or parenting style — this threatens the symmetry in the relationship because it implies one friend is superior to the other. Even well-meaning advice can cause tension if it feels like you are "coaching" or "talking down to" a friend — because it means you are no longer equals.

We can also do this to ourselves — feeling like a friend is prettier or more successful or better than us, and then beating ourselves up for it, can leave us feeling jealous and like our friends are a threat. And it goes without saying that it's hard to have a healthy friendship with someone you're jealous of or threatened by.

Support.

"There's some research that tells us that the number one thing women look for in their same-sex friendships is emotional support," Bayard Jackson said.

"You know, 'I expect you to have my back, I expect some shows of solidarity'. What makes that tricky is we so often don't articulate what support looks like because 'I think that as another woman you ought to know', 'I shouldn't have to say it you.'"

As women, we are often raised not to complain or voice our issues directly — we tend to communicate with cues, or "silenctly stack offenses" and then withdraw in the hopes that someone notices what is wrong and reaches out to us. The thing is, this just causes more conflict — now you're sad AND lonely, and the friend you cut off thinks you hate her for no reason and has shrugged it off and moved on.

"If you ask anyone, we all think we're giving adequate support — like who among us is going to say 'Yeah, I don't support my friends.' We all think we're doing a good job so there's obviously a gap here when there's those of us who are walking around feeling a lack of support."

Secrecy.

Secrecy is an interesting one, because it's not necessarily about literal secrets — it refers to the intimacy and trust that comes with self-disclosure, something that women do in close friendships.

Bayard Jackson said that "information is like currency in our relationships."

"[It's] feeling like you and I are in this mutually exclusive vault where we engage in self-disclosure. I share, you share because that is the glue of women's friendship," she explained.

"As soon as I start to have tension with you, I share less because me sharing and how much you know of me is probably indicative of how close we are."

It's why it can feel so jarring when you learn big news about a friend through someone else — it leaves you questioning your closeness, because why didn't they share that with you in your DnMs? Why weren't you in on the secret? Don't they trust you?

So, how do we sustain and nurture long-term friendships with women as adults?

Keeping an eye on whether the three affinities are being met and nurtured in your friendships is a great place to start in terms of understanding them and your needs.

Once you figure that out, it's easy to find the solutions: if you're feeling like maybe you aren't getting the solidarity you need, then that's something to talk about. Or maybe you've realised that there's a friend you share less with, and it's driven them away. Perhaps there's a friend who you're always giving advice to, and it's made them feel like the relationship is asymmetrical. Once you diagnose the problem, it's a lot easier to solve it.

Though, that being said, don't beat yourself up when you lose a friendship — research shows men and women change half of their friends about every seven years. It is simply normal.

Bayard Jackson noted that a trap we often find ourselves in is reminiscing about the past or how things used to be, but it's important to remember "that chapter is no more or it won't return for a long time." This may be disappointing, but it's something you have to accept and navigate.

Crucially, she said we need to be vulnerable — we need to be able to express it when we are scared of a transition in the friendship, and we need to be able to do so honestly and while centring our affection and love for that friend. So, instead of a passive-aggressive comment accusing a friend of "forgetting you", it's better to say "I really miss you and I'm happy for you but I miss us so what can we do about that?"

We could all be better friends, and learning to be good at friendship will help build better relationships in the future.

Feature image: The Mel Robbins podcast.