Many couples come to me with issues around how they handle their finances. While they have committed to a romantic partnership, they aren't always quite ready to be "financial partners" in their relationship. Often one earns significantly more income than the other and feels like they should have more of a say in how their money is spent. Often the couple still has separate bank accounts, even after many years together.
In my experience as a psychologist, "money" is rarely the main issue in their relationship. After many years of working with hundreds and hundreds of couples, my guess is that the money issue is merely a symptom of a deeper issue in the relationship, perhaps an issue of control ("I make more money, so I'm more important."). And underlying this, might be a fear of true commitment, a fear of deep trust and intimacy.
Consider the following question. It's NOT a judgment, just a question. Why is it that a couple still has separate bank accounts after a number of years in a committed relationship? If you can't trust each other with money, how can you possibly trust each other with your deepest feelings and thoughts, with your hopes and dreams? How can you truly be intimate? What else in your marriage is "separate" besides the bank accounts? How do you make the big decisions in your family? Or even the little ones?
If you'd like a "band-aid" for dealing with finances, here is the system that makes the most sense to me. Put all of the money earned by each of you into two joint accounts (one for savings, one for checking/bill-paying). For ongoing bills (utilities, mortgage/rent, etc.), just pay them directly. For every other shared expense or purchase, decide that you both must agree on the purchase, or it won't be made.
In addition, each of you will have a separate discretionary account as well, which consists of an equal amount for each of you each month. Perhaps you each will receive five percent of your joint earned income each month, to spend as you will. You decide on the percentage based upon your finances. No agreement from the other is needed for spending these funds.
However, as I've said, this system is only a "band-aid." I doubt that a couple would even be able to implement and sustain it for very long, before the deeper issues surface. I suggest that a couple in this circumstance begin to be more honest about their relationship with each other, and about each other's feelings and begin to share their vision of what they'd like their relationship to be.
If this is difficult, perhaps the services of a good marriage counselor or psychotherapist would be helpful. While financial issues are a symptom of relationship problems, they MUST be taken seriously.