Are you married? That changes my answer.
Unmarried, pre-children, we contributed as percentages to a shared pot for bills & food according to salary, and the rest was ours to spend as we liked on clothes, going out etc.
Unmarried but in a more established relationship with a mortgage, we did the above but the shared pot had more shared expenses - holidays, savings for property upgrades, car and travel expenses.
Married, we went to all shared but equal spending money for limited stuff. This meant maternity leave, kids expenses etc all covered. Clothes, phones, shared leisure expenses etc come out of the family pot for all, so spending money is just for if you’re socialising alone with friends or fancy a really expensive item you’re saving up for.
In my experience the least fair way is one partner (usually the bloke) pays the fixed bills and the other takes on the variable expenses like food and clothes and days out with kids. That tends to be quite unequal as circumstances change.
Basically good communication is at the heart of it all, deciding your joint priorities as a couple.