Penguins don't itemise our expenses for each other but we have a 60/40 split on most expenses because one of us earns more than the other. We do that via memory and occasional chats rather than a spreadsheet. Itemised billing of a loved one seems a little unusual but then people's attitudes towards money can be a little unusual and perhaps this was a way of ensuring fairness and equality without getting dragged into resentment and unhappiness.

What you can't argue, as you have very deftly pointed out, is that something you've given your tacit consent to over a period of three years is retrospectively an evil and abusive act. This is particularly true as the act itself is neither threatening, violent or abusive. This isn't transactional because there is no transaction - and once the system has been established Maddy would understand she would be footing half the bill at the point she ordered food/drinks/other things - and could factor that in.

I don't have a problem with an itemised spreadsheet, I just wouldn't like to get one. Not liking something doesn't make it morally wrong though. :o)