I write about the part of love most people don’t want to look at.
The math.
Most couples don’t break up over love. They break up over money. They just don’t know it yet.
The arguments look like they’re about something else. The dishes. The in-laws. The way one of you talks to the kids. The vacation that turned tense for no reason anyone could name.
But underneath almost every long-term relationship failure is a quiet pattern that started years earlier — a financial incompatibility that was visible from the very beginning, if either partner had known what to look for.
I started Cost of I Do because almost nobody is teaching people what to look for.
The work nobody told us we needed.
We’ve all been taught how to find love. Friends teach us. Movies teach us. A whole industry of dating apps and relationship coaches teach us.
But almost nobody teaches us how to evaluate financial compatibility — the single biggest predictor of whether a relationship will survive the next thirty years.
Not because the information is secret. Therapists know it. Financial planners see it every day. Older couples who got it right could tell you most of it, if you sat them down and asked the right questions.
It’s just that nobody has put it all in one place, in language a regular person can actually use, before the consequences become irreversible.
That’s what I’m trying to do here.
The math of a relationship doesn’t sit politely in a corner while the love does its work. It’s woven through every meaningful moment of the next forty years.
Why “Cost of I Do.”
The name is a small joke with a serious point.
When people think about the cost of a wedding, they think about the venue and the dress and the catering. Numbers in the tens of thousands.
But the real cost of I do — the financial weight of saying yes to the wrong partner, or to the right partner without doing the work — is measured in hundreds of thousands. Sometimes millions. Always in the form of choices you can’t unmake, savings you can’t recover, and years you can’t get back.
The actual wedding is the cheapest part of the decision.
What I write about is everything that comes after.
Who this is for.
I write for adults who want to think clearly about the intersection of love and money — without the cynicism of the personal finance world or the woo of the relationship world.
If you’re dating someone and quietly wondering whether you actually know who you’re with financially. If you’re engaged and feel there are conversations you haven’t had. If you’re already married and ready to fix what you’ve been avoiding. If you’re single and tired of repeating the same financial-incompatibility pattern in every relationship. If you’re a thoughtful parent who wants their adult children to enter their partnerships with eyes open.
This work is for you.
It is not for people who want manifestation routines, “five secrets your partner doesn’t want you to know” lists, or assurances that everything will work out if you just believe hard enough. There are a hundred products on the internet that promise those things. None of them work, but they sell well.
I write for the other audience — the one that wants the framework that’s actually true, even when the truth is harder than the marketing.
Six principles that shape everything I write.
If we disagree on these, we’ll probably disagree on most of what comes next. Which is fine — better to know now.
Love and math are not enemies.
Doing the math is not unromantic. It is, in fact, the most romantic thing you can do — because the math is what makes the love survive thirty years of weather.
Chemistry is not compatibility.
The two are independent variables. You can have one without the other. The couples who last are the ones who have both — and who learned, somewhere along the way, how to tell them apart.
Most patterns are visible early.
The signals you need to see in a partner are almost all available in the first six months. The trick isn’t finding them — the trick is knowing how to look without flinching.
Frameworks beat instincts.
Instincts are great for picking dinner. They are remarkably bad for picking partners. The brain in love is the worst possible state for evaluating long-term financial compatibility. A framework is what gets you past it.
The cheapest conversation is the early one.
The questions most couples never ask are the cheapest version of the conversation available. The alternative is having them later, in worse circumstances, with more on the line.
Honesty without cynicism.
The truth about love and money is harder than the marketing — but it’s not bleak. There’s a real version of romantic partnership that includes both deep love and financial peace. Most couples just never see the map.
The work, in three places.
Cost of I Do shows up across the internet in a few different forms. Each one is built to be useful on its own.
The 12 Questions
A 32-page PDF with the twelve questions every couple should ask each other before commitment. Including what each question reveals, what to listen for, and the defensive responses you’ll encounter. Free, no strings.
Get the PDF →The Million-Dollar Decision
The complete framework. 168-page book on choosing a partner for love AND lifetime wealth — plus three companion bonuses (scripts, worksheets, and a Red Flag / Green Flag Reference Card). 267 pages total. $47.
See the book →The Cost of I Do channel
Short videos exploring the patterns most couples never see — financial personality types, hidden incompatibilities, the math behind the love. New videos weekly. Subscribe and follow along.
Watch the channel →A personal note
One last thing, in case it’s useful.
I am not a therapist. I am not a financial planner. I’m a writer who has spent years studying the financial patterns that make relationships work or quietly come apart — and I write what I’ve learned.
What I share here isn’t a substitute for professional help. If your relationship is in crisis right now, please work with a qualified counselor. If your finances need expert eyes, work with a CFP. The frameworks I write help you see clearly. The professionals help you act on what you see.
I also want you to know: a real human reads every reply. If you write to me at hazel@costofido.com with a question, a comment, or a story about how this work has landed in your life, I read it. I don’t always have time to respond at length, but I read every one. That’s part of why I do this.
The other part is simpler: I’ve watched too many beautiful, hopeful relationships quietly come apart over financial incompatibilities that could have been seen, named, and addressed years earlier. The work in this book is the cheapest version of those conversations I know how to write.
Every couple deserves to have them. Most couples never do.
If this work helps even a small number of people have those conversations earlier, in better circumstances, with less at stake — then it was worth writing.
— Hazel McBride