When people couple off and get married, the vows usually include something to the effect of "for as long as you both shall live." The possibility of divorce notwithstanding, the goal, at least, is that your marriage should be permanent. In reality, though, it's not -- not necessarily because couples may split but because any long-term marriage is likely to go through a series of significant transitions that change it into a whole different relationship over time.

In this podcast, Motley Fool Answers co-hosts Robert Brokamp and Alison Southwick have in the studio Jennifer Petriglieri, an associate professor of organizational development at the international business school INSEAD. Author of the book Couples That Work, she joins them to talk about those personal and professional transitions and some tools that can help us to better get through them.

In this segment, she discusses a common quandary of couples in their 30s and 40s: The roles and lives they have constructed for themselves no longer fit. This doesn't have to mean divorce -- but it does demand the kind of mutual support that helps us get out of our comfort zones.

To catch full episodes of all The Motley Fool's free podcasts, check out our podcast center. To get started investing, check out our quick-start guide to investing in stocks. A full transcript follows the video.

This video was recorded on Oct. 15, 2019.

Alison Southwick: Let's move on to the second transition. Why don't you tell us the story that you relay in your book about Wolfgang and Heidi. It's like their story came out of a German folktale. I love it. Wolfgang and Heidi.

Jennifer Petriglieri: I got to choose the pseudo names through all the couples, and it was just so nice. The reason I love Wolfgang and Heidi's story -- and it's interesting that so many people pick up that story -- is because it's so typical.

It's that they've gone through their 20s and 30s, like many of us, in real striving mode. They're building their careers. They're building their relationship. They're also building a young family. And they took a choice, which is a traditional choice, in that his career took priority. She still had a good career, but she took more of the slack at home and he took more of the breadwinner role. They still both worked full-time -- they had full careers -- but that's how they split it.

And there came a point -- for them it was in their early 40s -- where both of them felt a little bit ill at ease with their choices. And this is really classic, because in our 20s and 30s, the path we take is always a combination between what we really want and social expectations. Your parents think you'd be a good doctor or a good lawyer and, lo and behold, that's what you do. Or there's some cool companies that everyone at college is applying to, and that's what you do.

This part -- and it sometimes serves us well -- served Wolfgang and Heidi well. They were doing well. They were enjoying themselves. They were growing a lovely family. But oftentimes, at that period of mid-career, we take a step back and think, "Is this really the path we want?"

And the answer for both of them was no, and in different directions. Heidi invested a lot in the family. She was still ambitious, and she felt, "I really want my shot of pushing a bit harder in my career." And she was someone who had a lot of potential. She was often getting tapped for management roles but was holding herself back because of that.

Wolfgang was in a very different position. He'd been really pushing ahead on the management track, and he had discovered a passion for coaching. He was like, "I would just love to give it a shot to be an independent coach."

But in the arrangement they were before, that was not possible. He was bringing in most of the income. He couldn't afford "to transition." And Heidi couldn't afford to step up because she was taking that role. And so for them, the solution for both of them was intertwined. They needed each other to shift so they could shift themselves.

And, of course, that solution sounds obvious when I say it like that, but it takes a lot for couples to get to that realization, and it can be a period, this second transition, of quite heartbreaking turmoil for couples. What happens is when a partner starts questioning their careers, and their lives, and their life structures, it's pretty threatening. We can think, "My goodness. Is this my fault? Is there something wrong with the relationship?" And often couples really start to unravel at this point.

I think the core of it is that the support we need in our couple at this time is quite different from the support we sometimes think of in a good relationship. So if we think of what a good supportive relationship is, we tend to think of a very British expression of the "tea and sympathy" model. That my partner is a good partner if they plump up my self-esteem and make me feel good about myself. Who doesn't like that? We all like that.

But at this stage in this transition, that's not the support we need, because what that support does is keep us close and keep us in the comfort zone. But when we're questioning -- "What do I really want to do and what's my direction?" -- we need to get out there and test new things and explore new fields.

And so what I find at this transition point is it's a very different conversation couples need to have. It's really about how we can support each other in a different way. Instead of having this real close, comforting support, we need a bit of a loving kick up the ass, if I can put it that way. Now there's a technical term for this, is we need a secure-base relationship, which means yes, we have that comfort and support, but we always have to push away to say, "You need to get out of the comfort zone," which means the comfort zone of our relationship, and out and look at different options and think of different ways forward.

It's very counterintuitive, because when we're feeling a bit wobbly, a bit threatened, our instinct is to pull up close, and this is exactly the opposite. It's almost a push away from the relationship. But what I found -- and this is what Heidi and Wolfgang did really well -- was when they could bake that kind of support into their relationship, both partners fared better, because both could explore and really think through these questions of direction, and then they could come back to the security together and figure out the way forward. It's a very different way of thinking about how we support each other.

Southwick: There is another couple you talked about in this part of the book where the wife wanted to explore more, so she was staying out late at networking events. She was meeting new people, and it sounded like her husband was feeling jealous of this time away. He was feeling, "She's off exploring new things and I'm staying here at home helping keep the home fires burning." It seems like that push and pull can be extremely [difficult].

Also with the couples in this chapter, it seemed like it took a really long time for them to even have these conversations [I think I want to explore more in my professional life]. This whole time, the other partner was sensing this tension, so maybe they were thinking, "They're having an affair." You talk about how this is a great opportunity to get divorced.

Petriglieri: That's not exactly how I put it in the book.

Southwick: It's not phrased exactly that way...

Petriglieri: I think there's two things. There is a reality. If we look at divorce statistics, they're not stable across time. There's peaks, and there's definitely a peak at this time of life. But I think silence is the biggest killer in couples, here. Our partner always knows when something's bothering us, whether we say it or not. And I think the reason people hold back is for many couples, life is kind of OK, so you can feel guilty. "Who am I to rock the boat? We've struggled to get here. We're in a decent position. I should just be satisfied with my lot."

The problem with that rationale is, it doesn't make the questions go away, so they build up and build up until they become these kind of really big issues, which they don't need to be, as I talked about earlier on.

The other thing is I think in this day and age, as a society, we rush to make decisions. There's a sense that, "I'm not happy in my career. OK, I'm going to spend the next two months networking and then by month three I'm going to transition and we're all going to be fine."

What this transition is really about is it's more of a deep psychological transition. How do I build a path that's my own? And it's a little bit like pregnancy. It takes nine months, and it's not good for it to be completed earlier. I think there's something about this transition that just takes a little bit of time where you need to stew in your own juices and really explore different options before rushing through it.

And if you rush through it -- this premature birth, if I can use that analogy -- it's not particularly helpful. There's another example of a couple who do just that. They switch quickly and then, lo and behold, six months later, they're like, "Hm, that was maybe not the best idea." It's really like, "Can we sit with the struggle, knowing that something will burst at some point that will be helpful for us?"

Southwick: Obviously, since we're talking about careers, there's the financial aspect. You talk about the importance, during this transition, of having made good financial decisions in your life, because that's what gives you the options to explore a new path. If you're not on a good financial footing, you need to just keep working, and you don't get to go out and explore and go eat, pray, and love your way around.

Petriglieri: I think there's two things in there. One of the huge benefits of being a working couple rather than one homemaker, one breadwinner is you do have a little bit more financial freedom. Even with that, there's very few of us who can eat, pray, love our way around the world. Let's be clear. But it gives you a slight bit of more wiggle room, so I think that's important.

But I also think it's important we get away from this black-white thinking that the only way we can transition is to take a year, sit in a cave, and meditate. That then the angels will sing and suddenly we'll know the way forward. That's not actually what the research shows happens.

How it happens, most commonly, is when people actually stay with their job and do inside projects. I'm spending some time going to networking events in the evening and reading books about different things. I'm talking to other people. Maybe I take a mini sabbatical at the most. Maybe I take on a volunteer project or a project on the side.

It's actually these things -- when you're still in your current life but adding things on top -- this is actually what the research shows is the most successful way to make these transitions. Now it would be lovely if we all had a year to go to Italy and do whatever else, but that may not actually be the most helpful thing in the end.