Quite often (say, 3-5 times a week), my mother will ask me something, I will answer, and she will question whether my answer is legitimate or whether I'm just answering what I think she thinks she wants.
I get where she's coming from, but with it happening so frequently it can get annoying, and I'd prefer she simply take my words at face value.
Me: "What are we doing for supper?"
Dad: "Mom and I are getting Ethiopian. You have leftovers."
Mom: "We're not going takeout for just you and me!"
Me: "Mom, what would you get if it were just you?"
Mom: "Well, Ethiopian. Or pizza I guess."
Me: "Okay, does the Ethiopian place have anything edible?" (It's well-known that I generally dislike Ethiopian food).
Dad: "Yeah, they have (rice dish)."
Mom: "You don't have to get Ethiopian, we can get something separate for you."
Me: "No, I'm fine with Ethiopian."
Mom: "Don't get it just on my account."
Me: "No, really, it's fine."
Mom: "It's fine, we can also get something you want."
Me: "I already have leftovers, so it makes sense to try something new, so that if I don't like it I still have other food as a safety net."
Mom: "Oh, okay."
Ideally I'd like to not have to go into the full explanation each time and to have my mother just accept my initial "it's fine" at face value. I'm worried that whatever I say to broach the topic, though, will just be seen as a veiled attempt to act out of her best interests and therefore disregarded.
So, just as the title says, how can I stop my mother from questioning my decisions out of selflessness?