Most couples don't fight about money. They fight about surprises. The card balance one person didn't know about. The car repair that had no plan behind it. The purchase that felt fine to one spouse and reckless to the other. Take away the surprise and most of the heat goes with it.
The cheapest fix I know is a standing money meeting. Twenty minutes, once a month, same day every month so nobody has to work up the nerve to request one. Requesting a money talk out of nowhere sounds like an accusation. A recurring one on the calendar is just Tuesday.
Keep the agenda boring. What came in this month. What's due next month, including the bills that aren't monthly, since those are the ambushes. One decision to make together. That's it. You're not redesigning your financial life every month. You're syncing the map so both drivers are looking at the same road.
I'll grant the obvious objection: the first few of these are awkward, especially if money talk in your house has historically meant trouble. That's normal, and it fades. By the third or fourth meeting it's routine, and routine is the whole point.
The meeting dies if it turns into an ambush. If one spouse arrives with a prosecution file, the other stops showing up, mentally if not physically. Ground rule: past purchases get thirty seconds of honesty, then the conversation faces forward. You're deciding what happens next month, and last month only matters as far as it helps you decide.
If you don't know what you'd even put on the agenda, start by finding out where the money actually goes. One month of real numbers gives you plenty to talk about.