My gf and I share finances this way: I gave her a credit card out of one of my accounts, the one with the best cash back. We use that anytime we are together.

My gf and I share finances this way: I gave her a credit card out of one of my accounts, the one with the best cash back. We use that anytime we are together. Restaurants, groceries, dog, flights, hotels, etc. the cash back goes back into the account. For everything else, we use our own cards and if there are any balance differences, like when I pay rent from my account, she just pays more on the CC than I do. This way we avoid sending money back and forth and we can track everything in one place. There is no burden when buying something knowing it’s fair for both without having to keep track of it later and ask for money from the other, etc.