My best advice would be make sure both of you agree upon a set of « rules » (I like rules so I don’t mind calling them that but feel free to use a different word lol) about what comes from what category. My boyfriend and I have a joint account that we each put 15% of our income into each month for shared expenses (groceries, going out, eating out, our cat, etc. ) and we have a list of what is okay to take out of the account and what isn’t so there’s no ambiguity. I found that communicating from the start about what’s okay and what isn’t for either of us really helped. Good luck!