Is your visitor from the US? If so, you REALLY need to clear this up/have a strategy.
When we were in the US we had friends that we weren't even staying with try to pay for everything and I really didn't want them to do that. I was mortified and worried about how I could repay them and also feeling like I just didn't 'get' what was expected of me (I am from the US originally.)
Conversely, I have had US friends here assume that I am paying for the lot when they come to stay. One friend started coming twice a year. Even the meals at home was a challenge - no stews, rice or pasta dishes - it had to be individual pieces of meat with everything. Not even offering to pay/contribute to for a take away that arrived. And no meal to thank us. I backed away when we were at Blenheim purchasing tickets...honestly, it got ridiculous.
Some people have the idea they'll extend the same hospitality to you "when you visit them" but we are not paying for four airline tickets to [this US city where this friend lives] any time soon and wouldn't be able to stay in her one bed in any case. Interestingly, when I was in this city for work on my own she was suddenly too busy to meet up...
That same work trip I was meeting with uni friends , one of whom assumed that my company would be picking up the tab for a meal for nine (no.) Also stung by an American colleague and his wife for a £300 meal when they were in London. My husband paid sort of by accident; he thought we were splitting it. Suddenly, no card was coming out and it was 'thanks so much.'
I probably sound like a stingy cow but I do think that 'the rational assumption' that you'd go Dutch on days out/food costs when you're visiting someone is not in fact universal.