"To maintain high levels of marital quality over time, couples also need to make their lives together exciting." — Arthur Aron
We had a Sunday last winter where nothing was wrong. The dishes were done, nobody was annoyed, there was a decent thing to watch. And somewhere around the second episode one of us said, a little too quietly, "we're kind of boring now, aren't we?"
Nothing was broken. That was almost the unsettling part. We'd spent years learning to fight better and repair faster, and we'd gotten good at it. Nobody warns you that not every threat is a fight. Some of it is a pleasant, well-run flatness.
That flatness has a name in the research, and a fix. The name is a stall in self-expansion, and it kept coming up as we read Dr. Gary Lewandowski's Stronger Than You Think. The book itself is broader than that, ten relationship myths and how to see past them, but Lewandowski is a self-expansion researcher, and the idea threads through his work. It also happens to be the one our whole app is named after: you don't find a finished relationship, you grow one.
Quick Answer
Self-expansion theory, developed by psychologists Arthur and Elaine Aron, says humans are driven to expand who they are by gaining new experiences, perspectives, and capabilities, and that a big part of why new love feels electric is that a new person expands you fast. The catch is that any one partner is a finite source of newness, so expansion slows, and that slowdown registers as boredom, which is an underrated, independent predictor of lower satisfaction years later. The fix is not fusing harder or grinding through the same routines. It is deliberately growing together again through novel, exciting shared experiences.
TL;DR
- The book: Stronger Than You Think by Dr. Gary Lewandowski Jr., a relationship scientist who is also one of the researchers who has carried the self-expansion model forward alongside the Arons.
- The frame: the book debunks ten myths, popular relationship beliefs that quietly do damage. We're pulling out the thread that runs through Lewandowski's own research: self-expansion.
- The model: the Arons' idea that we're wired to grow, and that relationships are one of the main ways we do it, by taking on parts of another person as our own.
- The aha: boredom in a long relationship isn't just a mood. It's an underrated risk, separate from conflict, and a sign that you've stopped growing together.
- The reframe: you can't manufacture the newness of early love, but you can rebuild the conditions for it, on purpose, this month.
- Where to get it: Stronger Than You Think at any bookseller.
The threat no one warns you about: pleasant boredom
Most relationship advice is built around conflict. Fight less, fight fairer, repair faster. All good, and we've written plenty about the argument that keeps coming back. But there's a large body of research pointing at a quieter problem that conflict advice doesn't touch.
In a study that followed 123 married couples for nearly a decade, researchers found that couples who reported being bored in year seven were significantly less satisfied by year sixteen, and that this held even after accounting for how happy they were to begin with (Tsapelas, Aron & Orbuch, 2009). The effect was separate from conflict, which is the striking part. Boredom wasn't just a symptom of a bad marriage. It was its own risk. The authors traced how it works: being bored slowly erodes closeness, and it's that lost closeness that drags satisfaction down years later. "It is not enough for couples to be free of problems and conflicts," as Arthur Aron put it.
This is the part that stopped us. We'd assumed that if we weren't fighting, we were winning. Conflict still matters, but a rut is its own kind of risk, and it's the risk that "we're fine" couples tend to miss. If any of this sounds familiar, it's the same terrain we covered in when couples drift apart, just with the science underneath it.
What "self-expansion" actually is
In plain terms: people have a basic drive to become more, to learn things, gain perspectives, get more capable, take on new identities. One of the fastest ways we do that is through another person. When you fall for someone, you don't just gain a partner, you gain their world, their skills, their friends, the version of you that exists around them. Psychologists call this "including the other in the self," and it's why early love can feel like your whole life just got bigger overnight.
That rush isn't only romance. It's growth. The excitement of a new relationship is partly the excitement of rapidly expanding who you are. Which leads to the uncomfortable mechanic underneath long-term love.
Why a partner "runs out of newness" (and it's not their fault)
Once you've absorbed a lot of someone, the rate of expansion slows. You know their stories. You can predict their order. The person hasn't gotten worse, you've simply finished the fast part of the download. In the model's language, any single partner is a finite source of expansion. The Arons argue this is an underrated reason love fades: not because something went wrong, but because growth quietly stalled.
We find this framing weirdly freeing. The flat Sunday wasn't evidence that we'd picked wrong, or that one of us had failed. It was the predictable result of two people getting good at each other. That fits something we believe generally: compatibility is the fruit of a relationship, not the entry requirement. The work isn't to find someone endlessly novel. It's to keep generating newness together. And boredom is a signal about where the two of you have gone quiet, not a verdict on your partner. Restarting the growth is something you can begin yourself, not a change you have to wait for them to make.
The researchers point to two ways back. You can keep discovering new and deeper sides of the same person, because nobody is ever actually finished, or you can go have new experiences together. Most couples reach for the second and forget the first. Both count.
Try it: name your rut out loud without blame, the way the researchers asked their couples. "We do the same things every week and rarely do anything exciting together" is a description, not an accusation. Saying it is what lets you do something about it.
Compatibility is the fruit of a relationship, not the entry requirement.
The fix is newness, not more niceness
The science here gets genuinely practical, because it has been tested. In a set of experiments, couples were assigned to spend time doing either something novel and a bit challenging, or something pleasant but ordinary. The couples who did the novel, exciting activity reported higher relationship quality afterward than the couples who did the merely pleasant one (Aron et al., 2000).
That distinction is the whole game. A standing Friday dinner at the same place is nice. It is not new. Niceness maintains. Newness expands. Most "we should do more date nights" advice quietly optimizes for the wrong one.
Try it: this month, swap one comfortable ritual for one mildly uncomfortable adventure. A class neither of you is good at beats a restaurant you both love. The small awkwardness is the point, that's the feeling of expanding again. For us, this became a running project rather than a one-off, which is also roughly why couples who stay a little ridiculous together tend to last. Feeling a little flat?
Grow yourself, and let them watch
Self-expansion isn't only a couple activity. Lewandowski's own research makes a sharper point that one of the book's myths circles too: a relationship should help you become more of a person, and support for your individual growth is part of what keeps the partnership alive. You expanding on your own gives your partner something new to include again.
There's a catch worth being honest about. The research suggests that growing on your own only helps the relationship if you actually bring it back and share it. People who chronically self-expand away from their partner tend to report less passion, not more. So the goal isn't two separate growth projects running in parallel, it's growing in a way you fold back into "us."
This was the hard one for us, mostly for Andy. As a deep introvert, his instinct was to keep his inner world inner and his growth private. The relationship didn't really open back up until he started treating his own development as part of ours, not a side quest he did alone. Watching someone you love become more themselves is its own kind of newness, and it's renewable in a way a fixed set of shared hobbies is not.
Try it: back one thing your partner is trying to grow into this season, out loud, this week. Ask about the new job stress or the half-finished creative thing and treat it as interesting, not as a logistics problem to manage. Curiosity about who they're becoming is one of the mindsets that makes people feel loved in the first place.
The rest of the book is honest about your other blind spots
We came for self-expansion, but it's worth being clear that Stronger Than You Think is broader than that. It's ten myths, and a few of the others landed hard:
- "True love should be perfect and effortless." He takes the same swing at the fairy tale that we do. Effort isn't a sign it's wrong.
- "The less we argue, the better." Not quite. Struggles handled well can strengthen a bond, which is why we think happy couples still fight, they just fight better.
- "We need to be closer." Counterintuitively, he argues you can have too much fusion, and that a little separateness leaves room to keep expanding.
It's warm, it's genuinely science-backed rather than science-flavored, and it mostly refuses to sell you the "fix your partner in five steps" fantasy. It puts the work where it actually sits.
Where this doesn't apply
Self-expansion is a growth tool, not a rescue tool, and the book is honest about this. Novel date nights will not fix contempt, chronic dishonesty, or a dynamic where one person doesn't feel safe. If that's the situation, the move is a professional, not a pottery class.
And the model cuts both ways. One of the book's myths is "if we break up, I'll be broken," and Lewandowski pushes back: when a relationship consistently makes you smaller instead of bigger, ending it can be the growthful choice. We read that as a caution against using "let's just try harder" to avoid an honest reckoning, not as permission to bail the first flat winter. Most stable, kind, bored relationships don't need an exit. They need a jolt.
Is it worth reading?
Yes, especially if your relationship is basically good and quietly running out of oxygen.
- Best for: long-term couples who aren't in crisis but can feel the spark thinning, and anyone who assumes "we don't fight" means "we're fine."
- Best for people who like the why: the science is real and he shows his work, without turning it into a lecture.
- Less essential if: you're in active crisis or there's a safety issue. This is a book about growing a healthy thing, not triaging an emergency.
Where this met our own work
We didn't come to this empty-handed. Building Growing Us, we'd organized our coaching around noticing when couples stop being curious about each other and start running on autopilot. Seeing it named so cleanly, with decades of studies behind it, and seeing that Lewandowski is himself one of the researchers on the self-expansion literature, was a satisfying kind of confirmation. Big credit to him and to the Arons for making the mechanism this legible.
It's also exactly why a book and a practice belong together. The book makes the case and hands you the language. A practice is what turns "we should grow together" into something you actually do on a busy Tuesday, whether that's a weekly check-in where you ask a question you don't know the answer to, or just a standing agreement to try one new thing a month.
FAQ
Why do I feel bored in a relationship that's actually good?
Boredom in a good relationship usually isn't a sign that something is wrong with your partner or your bond. It's a sign that the two of you have stopped growing together. Early on, a relationship expands you quickly, and that feels exciting. Over time you absorb most of what's new about each other and the growth slows, which registers as flatness. The fix is to deliberately create new shared experiences again, not to go looking for a newer person.
How do couples grow together instead of drifting apart?
Drift happens when a couple's shared life becomes entirely routine and each person's individual growth happens separately. Couples who grow together do two things: they regularly do novel, slightly challenging things as a pair, and they stay actively curious about who each other is becoming. A tool like the Growing Us app can prompt this. Its coaching mode notices when you've slipped into autopilot and nudges you back toward curiosity, but the mechanism works with anything that reintroduces newness on purpose.
Do date nights actually help, or is that a myth?
It depends on the date. Research suggests that novel and slightly challenging activities improve relationship quality more than merely pleasant, familiar ones. So the same restaurant every Friday maintains the relationship but doesn't expand it. A class, a trip, or an activity neither of you has mastered does more, because the small stretch recreates the feeling of growing together.
Can you fix a boring relationship without breaking up?
In most cases, yes, if the boredom is genuinely boredom and not a cover for contempt, resentment, or a safety problem. The evidence points to shared novelty and supporting each other's individual growth as the levers. If trying those consistently changes nothing, or if the relationship reliably makes you smaller rather than bigger, that's worth exploring honestly, ideally with a therapist.
One small place to start
Pick one new thing to do together before this month is out, and let it be a little awkward. That awkwardness is just the feeling of expanding again, the same thing that made the beginning feel so alive.
You don't find a relationship that stays exciting on its own. You grow one, and you keep growing it. If you want the daily version of that to be easier to remember, we built Growing Us around exactly this: small nudges to stay curious, a coaching mode that notices when you've gone quiet, and prompts that keep you learning each other on purpose. None of it does the growing for you. It just makes it harder to forget.