Every relationship has issues where each sees things somewhat differently. (Money, in laws, children, religiosity, value differences, division of responsibilities, etc.) Too often, these issues only get attention when couples are fighting about them.
When an issue is not addressed in constructive ways, negative energy around the issue is stored up and can easily get triggered. If you never talk about money in a constructive way, then when a credit card bill comes in or the heater breaks or another expense comes up, an argument or simmering frustration may crop up. In this mode, instead of talking about the spending plan (or budget), the fight is about the current bill. You won’t get to the core of the issue at this point.
Instead, set aside time to deal with the issues ahead of the time when events will trigger them. Yes, it might seem hard, or counter-intuitive, to talk about conflict areas when things are going well. But that is the best time. You don’t have a particular fire to put out and you are calmer and more levelheaded. You’ll have a much more productive conversation around the issue.
If you don’t address the issue, you’ll be walking on eggshells, just waiting for the next fight to erupt. And it will happen since there are unresolved issues.