So, there's separate accounts, there's separate wealth, and then there's separate budgeting. These are not all the same thing.
-Separate accounts just means that the actual accounts are separate and that the money isn't directly pooled together. This indicates nothing about how the money moves around or if expenses are split.
-Combined accounts means literally having joint accounts or pooling money into one person's account.
-Separate wealth means that whatever assets are built up, there is a clear organization as to which assets belong to whom. So, here, if a couple isn't married and only one person owns the house/ has a pension/retirement account, those assets belong to them alone.
-Getting married automatically combines wealth in most jurisdictions to some degree, but the details can be complicated. There are many ways in which wealth can become entangled, home ownership is a big one.
-Separate budgets means agreeing on whatever proportion of shared expenses each contributes, and then basically keeping your nose out of each other's spending otherwise.
-Combined budgets can consist of many different forms, and often involve all/most spending decisions to be shared.
A couple can have any degree of combination of the above aspects of separate/combined finances, meaning that there are endless ways to arrange it for any given couple.
The key is to talk about it openly and in detail, establish mutual priorities and structure an agreement from there. Think about how you would handle it if it were a business partnership, you would be very focused on what's fair for both parties, so treat relationship finances the same way.
There is no right answer, there's only what's right for you as a couple, so talk, and keep talking because what's right will also change over time.
