I guess I must just have this weird habit of when someone offers me something and I don’t immediately take them up on it I don’t expect the offer to still be there later. Having lived in many roommate situations and being a full adult I don’t pin my happiness on whether my housemate saved me something they bought and was nice enough to offer yesterday. If it’s there then great. But if I was so looking forward to ice cream that I would have a meltdown if I couldn’t get it, then I would 100% take care of that shit myself and go to the store before I got home. Or if I know my roommate binges when stressed at least text them and ask if the ice cream is still there before you get home. But I just can’t imagine a world where I wouldn’t take care of my own grocery needs myself, with a romantic partner sure, but acting this way and blowing up at a roommate for eating their own food? Wild.

I think OP is NTA but they should stop sharing with the roommate, just be responsible for each of their own stuff.