I'm pretty sure I'm not being unreasonable, I more want some help with how to deal with this situation.
DM grew up in a very different world to the one I now live in - with a large house, household staff, regularly entertaining visiting dignitaries, different dining sets for different occasions, finishing school etc. By contrast, I live in a very normal & casual suburban mid-terrace house with no staff, just a cleaner once a week. My plates and cutlery are mostly from IKEA.
Pretty much every time she comes round she points out that we don't own some sort of vital object (or that the one we have is subpar) and then buys it for us. It can be small items like corkscrews and gravy boats, or tablecloths and napkin sets, but sometimes it's larger items like footstools, lampshades, paintings etc. These are things that we don't want or need.
I'd describe myself as an aspiring minimalist, in that I put a lot of thought into what comes into the house and am always trying to own less. But more importantly, I have no space for these things. Where possible I just store them away in the shed or spare room and bring them out when she comes over, but it's getting more and more frequent. She also feels a sense of ownership over the items and will look around and say 'where's that xxxx I bought you?' It's tiresome.
In the past, I have gently tried to ask that she doesn't spend money on these things but she gets extremely sensitive and somehow sees it as a rejection of her and the way she lives. What is a kind and non-judgmental way to say 'please stop buying me things'?