This can help you eliminate spending on some things you’re both paying for (it happens!) and get a sense of your actual shared bills to utilize your joint account better and start spending as a team.
Rather than expect the more free-spirited person to become the master of spreadsheets, think about how they can best contribute to the financial relationship.
By creating buckets, for example, using the 50/30/20 rule (50% on needs, 30% on wants, and 20% to savings), you can start effectively planning with your money rather than just saving and spending sporadically.