Then they have their own account that you transfer $X/month into. If you can't agree as a couple on what each person should be spending, then the relationship is on bad footing to begin with.
If you offload your responsibility of paying your expenses upon another, you surrender that freedom to them.
If a couple wants equality, have separate finances and incomes and make agreements as to how any financial matters that must be handled together should be handled.
Most couples will try to cover shared expenses with their combined income and then equally distribute the remainder, so that neither of you is left wanting. Of course if you're the one making significantly more (or a sole income provider) you might see this arrangement as mooching or unfair as you're contributing more. But there's more dimensions you can contribute to in a relationship than just financial, and hopefully both partners can recognize that.
Budgeted amount for say toilet roll.
Decide whose bank account to use for it.
How to re balance as expenses change.
For each expense or group of expenses.
Each spend kinda needs to be tagged. It is a lot more work.
Might be OK if you have no kids and are renting.