Hmmm yes, I do get what he's doing, and why it's so unpleasant.
He's subtly changing the tone of the conversation so it looks like you're stupid/a child/he has power over you, and particularly in front of other people.
In my youth, I got some comments from my parents, a couple of men I dated. Not overtly aggressive, but just snide put-downs.
"why is your face like that? why are you putting that face on?" (my face is just normal/expressionless)
"standing around in la-la land"
"acting like you're dumb"
"why did you do X?"
In none of these circumstances was I actually doing anything impractical/dangerous: I'm actually fairly high-achieving and intelligent, organised and socially proficient/popular.
I really don't know what the solution is to people like this, or if there is one.
I do feel the way they act - the little digs and criticisms - is a reflection of their own shit/insecurities? They feel awkward, so they get off on projecting those awkward feelings on whoever they're with, so then they can go "oh look, she's the weird/silly one".
(my parents are academic/social failures and the men in question the same)
Like Imperial says, it's exhausting having to stand up for yourself all the time, your partner should be the one who supports you.