There is a huge difference between just not sharing something and keeping secrets. Among the comments here, especially those with traces of seriousness, there seems to be a bit of confusion. Having an aspect of one’s life that is secret and kept away from a spouse is a powder keg. The discovery is often enough to create major problems. Similarly, there are plenty of issues that one spouse can experience that are not needed in the interaction, and bringing them in can create wedges. A few mentioned about having a bad day at the office. There might be many ways to deal with this. Arriving home and mentioning it in the context of reaching out for support can be a positive thing. If the spouse then digs into the issue, offering opinions that are irrelevant, could create potential for conflict. So it’s not simple, but the distinction above is one of the basics in relationships.
Having separate bank accounts can work for some, but transparency is critical. Maintaining schedule structure with knowledge of where the other goes is a great idea, critical for many couples.