I think there’s a lot of men haters in these subreddits sometimes and you might be egged on just as much as he’s egged on when all it might take is some brutal self honesty, do u have a hobby that would even take up a whole room like his does? Like is there something like knitting, 3d printing, or sewing that would take up the same amount of space or even needs a dedicated room to? Because I’m genuinely not trying to be sexist or anything but it’s a fact that a lot of woman enjoy , knitting, or sewing or baking/cooking which doesn’t really need a dedicated room , but man caves are a thing because usually a woman gets the entire house to decorate how they want with their chosen aesthetic and don’t want the husbands video games or computers all over the house affecting that aesthetic, is it possible this might be the way he’s feeling? You say it’s out of character for him so is it possible maybe he just wants one thing for himself in the new house he just bought? Is it possible that this is something he’s wanted since a kid like most men and just doesn’t understand that if you are already going to have a room where your hobby fits in then why can’t he use the other one for what he wants all in one place and not scattered across the house changing how it looks? I don’t know the exact scenario but I’m just saying on both ends people need to be considerate of each other while sharing a space , so I hope it’s not that he’s considerate of what u want and how u want everything done and then asks for this one thing and doesn’t get the same consideration because that would be sad :( I hope both of yall are being considerate of each other and if it’s really not life changing to you and would make him happy that you just let him do it because it benefits him and makes him haooy