I keep my money separate from my spouse — and it's key to happiness in our marriage

• Money is a common source of stress and arguments for many couples.
• In a marriage, couples sometimes think that they need to share everything — including bank accounts.
• However, having separate finances allows you to be in control of your spending, reduces the stress of having a joint bank account, and allows you to have fun with your money.

When I first got married, I thought my spouse and I were supposed to be attached at the hip in all things. Over time, I found that I needed more breathing room than the close embrace of early love allowed. For me, that meant separating my money from my wife's.

"Every good marriage is based on an awful lot of separation," Steven Nock, a professor of sociology who studies marriage at the University of Virginia, told WebMD. "People need to have a separate life and existence to feel validated as individuals. They can't live solely as somebody's partner."

For many couples this happy separation extends to their finances, as well as their social lives.

Our money separation felt harsh at first. I had decided to pay down some debts and improve my financial IQ, and I knew I needed a separate checking account to learn money management. To my wife, this seemed like a slap in the face. Over the years, however, our separate accounts have given us both the freedom to have a little fun with our own money, while still being financially accountable to each other.

I’m not alone in wanting to maintain separate finances from my spouse. TD Bank’s 2017 Love and Money Survey found that 51% of the couples they surveyed combined all their finances, while 34% kept some money separate and 15% didn’t share money at all. The trend is stronger among millennials: 29% of couples under 34 have no shared accounts.

There are a number of reasons why married couples are joining the trend and keeping their finances separate from their spouses. Here’s why.

SEE ALSO: How my husband's trust fun affects my life

1. Two bank accounts are better than one

Mingling your money can add stress to your marriage, too. If you and your spouse have divergent spending habits and financial priorities, you can either fight about it or give each other some space to be different.

You might be happier if you didn’t know how much money went to piano lessons or that cute little Kate Spade backpack. That’s certainly true for some couples.

2. It doesn’t have to be all or nothing

Some couples take a “yours, mine, and ours” approach to personal finances. Each spouse has a separate account, and both contribute to a joint account to pay household bills.

My wife and I have come up with a version of this approach. We each have our own checking account as part of a jointly-owned credit union account. We have a joint savings account for reserves and another that we both contribute to for mortgage and property taxes.

In a pinch, either one of us can access the other’s checking account. Over the years, when one of us has made substantially more money, it’s been easy to transfer funds to support the other.

Best of all, I don’t have to weigh in on the new bike helmet she wants, and she doesn’t get to have an opinion about how many dresses I need to own (a lot). We can look at each other’s accounts if we want to, but we generally don’t.

I talk about money with my wife, and we make big financial decisions as a couple. But we stay in our own lanes for the day-to-day stuff. I think that’s the secret sauce for a happily married financial life.

3. Some of your finances are unavoidably intertwined — such as sharing a home together

There is a lot to be said for joint bank accounts. If one spouse dies, joint accounts usually give the survivor immediate unrestricted access, according to legal website Nolo. If your accounts are separate, then you’ll probably need documentation that proves you have a right to the money, and you might have to go through probate before you can touch the funds, Nolo reports. This can add stress to an already stressful time.

Joint accounts also foster financial transparency. According to the TD Bank survey, 13% of respondents said they concealed some part of their financial lives from their spouses. Millennials were much more likely to have undercover money (30%) than couples over 55 (4%). Secrets included clandestine bank accounts, and undisclosed credit cards and student loan debt. Worse yet, 35% of respondents said they had no plans to ever share their money secret with their spouses.

Financial cover-ups can send a marriage onto rocky shoals when they come to light. A recent "Dear Sugars" column had a term for this: financial infidelity, which associates hiding financial information as a form of betrayal to your partner.

Even if you keep your finances separate (in fact, especially if you do), there’s no way to avoid talking about money with your spouse. When you live together, your financial lives are unavoidably intertwined.

When my wife and I first separated our bank accounts, we tracked how much each of us spent on household items such as utility bills and groceries. I was surprised to find that I contributed just as much by purchasing household supplies and food as she did by paying our fixed expenses for things like car insurance and the electric bill.

Over the years, we’ve renegotiated who pays for what, as our financial and living situations have changed. What hasn’t changed is our commitment to sharing financial information with each other and making big money decisions as a team.