Repeating ourselves is pretty straightforward; we say the same thing multiple times. I'm not sure how aware we are of repeating ourselves, as when I bring it up to a wife or husband in couples counseling, he or she seems surprised. So begin to notice if you are a repeater.
"You" sentences, on the other hand, are either poking at our spouse, or are another way of brushing aside what our mate has said; by turning it back on him, getting the heat off of me. They are accusatory, critical, or contemptuous.
Let me give examples of the "You" sentences: You never listen to me. You never take my feelings into account. You're too emotional. You don't pay attention to money. You always do what you want. You don't load the dishwasher properly. You don't drive right . . . fill in the blank.
Our brain is wired from earliest evolution to survive, and when it perceives threat, we will either fight (yell), flight (walk away from our mate in the midst of an argument), or freeze (go silent, hunker down until it's over).
Often couples have differing reactions to perceived threat (i.e. one yells, the other either freezes or flights). So in addition to not feeling heard or understood, their primal reactions are misunderstood and that can escalate the interaction even further.
Note: These differences can show up on the intimacy side too, often called the pursuer/distance or wave/island dynamic.
We have to get out of these cycles I together====.
Recognizing them is the first step. Try just this one experiment this week: If you are the talker, say, "I don't feel heard," or if you are the listener, say "I'm not sure what you mean by that, can you tell me more?"
Leave out all the rest (the editorial, as we like to say at our house). No repeating, no "you" sentences.