How have you debated and disagreed and never once lost your temper?
I just don’t lose my temper very easily? If I feel myself getting annoyed I take myself out of the situation until I’m calm. And most stuff is minor enough that it doesn’t really warrant losing my temper - everyone has annoying habits, and it is generally irritating stuff (like the washing up being left) rather than serious stuff that I get annoyed about.
How pointless would it be to start an actual fight about the bloody washing up, when the responsibility is 50% mine and DH would probably just do it if I mentioned it. I suppose if I thought DH wouldn’t listen to me, or pay any attention to my feelings, I might feel I needed to shout to be taken seriously. But that would be pretty damning for our relationship.
I have a toddler and have never lost my temper or shouted at him either. I have felt myself getting annoyed plenty of times, and have either handed over to DH or left the room for a moment and counted to ten. Again, a toddler being annoying never genuinely warrants losing my temper, once I have a bit of distance and perspective. Is it annoying when he tips his cereal on the floor, yet again? Yes. Is it serious enough for me to lose my temper about it? Not in retrospect, no. He is 3, I am an adult.
People who do have proper rows with their partners on a regular basis, what exactly are you fighting about? And do you think it actually warranted a shouting match the next morning, or do you feel that one of you over-reacted with hindsight?