Aunt: I’m going to Walmart, do you need anything?
Me: no thanks, I’m going there later to do some shopping myself
Aunt: But we could combine trips! It’s wasteful to both drive there on the same day! The responsible thing to do—
Me: ok, I give up. Please get me cat litter and cat snacks.
Aunt: Ok!!! :)) Which ones? And what isle? What color is the package—
Me: exasperated Are you serious? I caved and gave you what you wanted. Now you’re asking for more information? I told you I wanted to do my own shopping, and you fought me on it. I’m making a peace offering by giving you two items to buy for me, and you’re saying I need to go find the names and package colors and isle numbers? Please just be satisfied with what I gave you.
The thing that she wants is to feel good about buying me something. But I don’t want that. That’s the disagreement.
I imagine most people would see me as the asshole here: she can’t buy the right item if I don’t tell her what it is. But I clearly don’t care about those details; if I wanted something specific I would have told her that. The only reason I mentioned them was to appease her. I’m giving her something she wanted, something I wanted for myself, and she’s demanding more.
I think your aunt was trying to be helpful and efficient by doing you a favour. And it’s okay to not know everything like a store employee when asked questions like “what aisle”, just be like “I dunno what aisle” or “look in the pet section for cat stuff”.
If you didn’t care which type then fine, say as much, if you do care then just send the online listing, write down or print out (if your aunt is computer-challenged) the kind you want. Your aunt is preemptively trying to avoid you being disappointed by getting the wrong litter/snack. It’s like 3 minutes of effort for you to save an hour or two of your day.
If you for whatever reason really want to go separately on your own then just insist “I want to go pick out the specific package myself”, but leaving things ambiguous while getting upset and hostile over it is good for nobody.