I'm fortunate that there's no need to hide my purchases from my other half. She and I both thankfully see eye-to-eye on our expenses, and we trust each other that our "fun" expenditures don't impact other financial goals we've set. We have a budget that we adhere to - and a hobby bucket is just as important as a college savings plan, or retirement savings. This extends into how we manage our mortgage, auto loans, future goals, vacations, etc...
Financial trust is an important aspect of a relationship because it permeates into all matter of our lives. All discussion points for any activities ultimately comes back to cost, and we spend money where we see value. It would be a relationship problem if my wife didn't see my outlets as being important to me and vis-versa. How this is organized is not important (single account, multiple access accounts, individually accessed accounts) - what IS important that that we are on the same page.
Don't get me wrong, my wife raises her eyebrow at me at times but she knows I wouldn't sacrifice, say a family vacation for a drone, or dip into our emergency fund for the next new gaming machine.
