Help please - he says I don't know how to have a conversation.

Hi. 
My husband and I have had a few fights lately - the same ones we always have and then ignore for a few months. He says I don't listen to him but I really feel like I am listening.

He says the evidence that I am not listening is that I don't acknowledge what he is saying and just repeat the same things over and over again such as "I don't agree, I think x" or "I don't understand y."
He says he feels like he is talking to a wall and that I don't even know how to have a proper conversation and he obviously feels really hurt and frustrated but I don't know what to do about it.

I came up with some theories such as maybe I just can't process what is being said quickly enough or that I often don't realize that casual conversation has suddenly turned into something important until it is too late - but I don't know if those are even the real issue?

I am hurt too that he thinks I don't listen because to me I am trying very hard to listen. And listening and immediately providing the appropriate feedback are not necessarily the same skill? To me anyway?

I just really don't know what to do because in the moment I don't even know I am doing anything wrong.
It isn't until after it turns into a fight that I either think "this is obviously more important to him than me so I should apologize" or "I don't know why this is such a big deal but I still don't agree so I am just going to sleep it off."

Any advice? Resources? Similar situations?

Thanks!