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 the first major upheaval in the average couple's postmarriage life: the arrival of children or the career move that requires a move.

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.

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This video was recorded on Oct. 15, 2019.

Alison Southwick: Jennifer Petriglieri is an associate professor of organizational development at INSEAD. Her book, Couples That Work, looks at the experiences of couples around the globe and how they thrive in their relationships and at work. Thank you for joining us!

Jennifer Petriglieri: It's great to be here! Thanks!

Southwick: I was on the old Facebook the other day, and a friend of mine had posted she was reflecting on her past 15 years of marriage with her husband. She had all these pictures of them when they were younger, and it was so great.

And she talked about the idea that you and your partner don't really have one marriage -- but instead you have three or four marriages with the same person -- because you grow and change together, and the people that you were when you got married are not the same people that you are as you mature and as you are today. And I thought, "Well, that timing is pretty perfect," as I'm reading your book.

That's really at the crux of what you wrote about in your research; it's the idea that people change -- their wants, their needs -- both professionally and personally, and there are tools that you can use to navigate these tough transitions. How did you decide to start writing this book?

Petriglieri: It really came from my personal experience. I'm in a working couple like most couples out there, and we were at a point in our lives when things were tough. We had two under-twos. We were both striving to get ahead in our careers. And to be fair, my husband did very much his fair share of the washing, the cooking, the cleaning, and all that sort of stuff, but we felt like we were hanging on by the skin of our teeth.

I did what every good academic girl does. I went to the library and tried to find books, advice, anything that could help, and really I found either stuff that told me how we should divide up the laundry or things about even these power couples who had everything sorted, and this really was not helpful.

And I knew this wasn't just my experience. It was the experience of my friends, my family, my colleagues, my students, and I really came to the point to say, "If no one has done that research, then I'm going to do that, and I'm going to write that book." So that was really the motivation.

Southwick: Your book goes into three main transitions that couples are going to go through, typically. Everyone's different, but you found that there were some common threads here. You talked to so many different couples. Let's just get into the first transition.

For most of us, we find a partner. Maybe we get married. Maybe we move in together. Not a lot of changes. It's pretty smooth sailing. But then upheaval comes, and you found that was usually in the form of having kids or when one partner opts to take a job elsewhere.

Petriglieri: Yes. Essentially, when we first get together, we still have parallel lives. We're pursuing our careers. We've got our friends. We just lay it on top, this wonderful relationship. Life is rosy, and it never stays that way.

Southwick: No, it doesn't!

Petriglieri: And what tends to kick off that first transition is either a great career opportunity which presents a hard choice. I get a job on the other side of the country. The parallel living. Do we move together? Do you follow? Do we go our separate ways? A baby, which anyone who has kids will know, that really does end parallel lives.

Oh! Maybe if we get together later in life, and this is the decision, do we blend families from an old relationship? Again, real end to parallel lives. And at that stage, couples have to face a fundamental question. "How do we make this work? How can we combine our lives into one joint path in a way that we can both go after the career goals we have, but also have a decent relationship and a healthy family around that?" And it's a tough decision.

Southwick: It is. You had a piece in The Wall Street Journal that I read, and we talked about this before we turned the microphones on. A lot of the articles, so far, about your book have really zeroed in on the couples contracting, and so people really focus in on that cold word "contract."

I mean if you read the comments section in The Wall Street Journal piece that you did, they're getting all cranky about [...]. "We just listen to each other, and love, and what's this with the kids and their contract?" And they totally miss the point, because I'm sure they didn't read past the headline that what you're talking about is really having thoughtful conversations that lead to a mutual understanding about what makes your partner tick.

Petriglieri: Exactly. And I think the problem with that first transition is we tend to be rabbits in the headlights. We reach this decision point, we go into panic mode, and we almost always think practicalities like child care, geography, spare bedrooms, these kinds of decisions. And, of course, we need to fix the practicalities, but what I found very strongly with couples who just focused on that is this is the path to hell, because they're not doing it with any logic in mind. They're putting the practicalities before the principles and the logic of their relationship.

So couple contracting -- and when I talk about contract, I mean a psychological contract, and not a legal one that we sign in blood and put in a safe forever.

Southwick: If that works for you as a couple, that's fine...

Petriglieri: That's fine, but that's not what I meant. It's really a way of discussing, "Look, what are the things that really matter to us?" And once we figure that out, then we can make choices more mindfully and layer on the practicalities.

And those things may well be career goals. "This is really important to me to pursue." It might be things like, "How can we stretch our life in a way that gives us enough time for other stuff on the side?"

It might be about financial stability. "How can we build financial stability? Maybe five years down the road I can try entrepreneurship or I can do a career move."

It might be about the type of family we want. "I really want us to be a couple that's deeply rooted in our community. How are we going to set up life that way?"

And the couples who started there really did much better, because they had this set of principles that they could then make decisions from, and they could really honor each other's desires and ambitions in their relationship.

Southwick: As you were talking about how to have this conversation [in your book], you talked about [how to] have a conversation around values. Around boundaries. Fears. And [I thought], "Oh, yes. This is all great. This all would be a wonderful conversation." But it feels like you would need a third person in the room to really nudge you both forward. "What do you really mean by what you value? What do you really mean [when you say you want to give your kids] the best childhood possible?" It sounded like you needed someone else in the room to help you.

Petriglieri: I think that is a common feeling among many people. These conversations are frightening, and I might get them wrong. First of all, it's not just one conversation. It's really, "How do I build a habit of talking about these things?" It's not that if we don't agree on everything tonight, this is never going anywhere.

Secondly, in many ways, these are the conversations we all crave. How do we talk about what we really want out of life and plan this? And my experience when people start having them is they actually quite enjoy them, because this is the stuff that matters to us. This is what life is made of.

So I think it's just about biting the bullet and starting. Sometimes people will say to me, "Do we need to go away for a romantic weekend and hire a log cabin?" I'm like, "Well, if that's what you want to do, that's great." But really you just need half an hour or 20 minutes at the end of the day, with your mug of coffee or glass of wine, and just spend some undivided attention with each other, starting to talk this stuff through. It's not rocket science. It's really about how you are going to invest in your relationship.

It's really funny. When we think about our careers, we don't think twice about investment, right? We don't think twice about taking some time to sit down and think, "What's the vision for my career?" How many times do you think, "What's the vision for my relationship?" We don't think about how we're going to invest in our relationship, and yet we know, over time, that this is the thing that matters more than anything else in our lives: to our happiness, to our long-term fulfillment, and to our health. We know that our health is determined on our relationships, as well. So it's really about switching our mindset and thinking about investing in the relationship.