For our whole M I basically was handoff the money, just made it and my wife would do anything with it. This caused some big problems with finances, to the point that she got us into foreclosure twice (!). So before BD we were talking about me taking that over and splitting accounts.
Well, when BD happened I had opened a new account for "big expenses", I asked her if she wanted to join it so she can see what's going on. She said "I don't want any new accounts with both of our names".
So I've split my check, and made it smaller and smaller into the shared account. I've found that the more money she sees available in an account the more she spends, so I've been able to make the money last longer. I told her she can use it for kid expenses, minor expenses, like you describe. But yeah sometimes it runs very low (last yesterday) and she feels frustrated I know to have to ask me to fill it up. It's not my intention to frustrate or control her with it, but I know she perceives it in a negative way.
Last night when I used my own card for her gas, she texted me the amount when she was done. I didn't ask her for that, so that's an example.
