My boyfriend (been together 4 years) will always respond with "I didn't mean to!", when someone points out to him he did something wrong. It always sounds slightly accusatory when he says it, like he wants to say: "I'm only human, stop blaming me!".
Examples: He stepped on my bare foot with his boot. I said a genuine "ouch", because it hurt quite a bit. His reponse: "I didn't mean to!" Another time, he was asking me for photography tips. He was taking a photo and I heard his shutter time was too long to use without a tripod, which results in blurry photos. I gave him some feedback on shutter times, to which he responded again: "I didn't mean to!" A different time, he went to get take-out and got us something extra that I really like. I said, happily, "Oh, you got X!" He: "I didn't mean to!"
He doesn't just do it to me. He does this nearly every time someone points out he did something. In some cases, I feel an apology is more warranted, like with stepping on the foot, in other cases, just an "okay", would be enough, like with the photo. In even different cases, I feel the response is completely out of place. I think this response may be partially my and my mother's fault. He'd previously say "sorry" in similar situations, but we would often tell him to "stop saying sorry for everything".
His reaction feels off to me. I'm an aspie and I don't always 'feel' people as well as others, but I can tell his reaction is at least different from the norm. It confuses me and I don't know how to respond to it. He is not diagnosed with any form of autism, but he shows some traits. He is aware of that. Note: I am 100% certain that it isn't some kind of joke or meme.
The outcome I desire:
It seems the problem stems from deeply rooted anxiety. I would like him to stop apologising (saying "I didn't mean to"), for every single thing, especially if not relevant. How can I help him realize that he doesn't need to?
What I've tried
I have mentioned to him that I think his response was unnecessary before, but his response to that was, ironically, "I didn't mean to!
Update: I’m not overly annoyed by his answer. I want to help him with it though.