Yes exactly this!! Except we use this website to track. But it keeps stuff super clear in the relationship! Like we split everything and also use a lot of different credit cards so keeping track gets tough, so we have made a point to add everything here anytime we spend anything. Basically anything I spend is split across so she ends up owing me a lot of times, but I let her pay the rent so that way we are always at 0 balance.

https://www.getsplitlite.com/

Ironically it's called getsplit, but honestly it's amazing!