I’ve been doing that with my fiancee for 1.5 years now and I love it. There’s never any concern about either of our spending and we try to equalise our ‘allowance’ parts so that we both feel comfortable buying things for ourselves.

I have to say though, that’s coming from a context where we both earn more than enough for upkeep -+ fun stuff. I can imagine this wouldn’t work if you’re trying to make ends meet every month.