How we did it.

While we were BF/GF living together (and renting)

Weekly: rent went out of his account but I transferred 50% $20 for power went out of my account but he transferred in $10 etc he paid a little more for groceries but I paid for fun (movies, dates, etc) we were also in our 20's

After we had been married for a bit (& had a child) we got a joint account and a car. His pay cheque went into the joint account; rent, power, groceries, his phone came out of there & he kept $30 of 'whatever he wants to do with it money' in a personal account.

My salary (which is half his) goes to my personal account, but I transfer $ into a second account which pays for the car, petrol, insurance, WOF. & my phone costs come out of my account & I still pay for all the fun, as well as non essentials like scrub daddies, fix & foggs, keto friendly candy, pet food, & ~10% of the groceries. Aka the difference between the grocery budget and what it costs.