I hate to say it, but your partner reminds me so much of my own father growing up.
I have vague memories of things being pretty good when I was very small (and without much voice of my own), and he would tickle me and play with me. I loved him with all my heart.
In those early days, I never remember seeing him lose his temper, but I do remember overhearing my mother very sternly telling him that if he ever laid a hand on her or the kids, that she would leave. Its the first memory I have of her ever 'talking back to him', as she was normally very passive and 'keeping the peace'.
As I grew older (around 8), and my mum left the house to start working (they had both been unemployed until then), suddenly things started to go wrong with my dad, and in many ways it was as if he thought I should fill her place now she wasn't there.
He began to get irrationally angry for things I was meant to have done that I didn't even know I was supposed to (like washing the dishes or putting laundry on). Nothing I did was right, everything was criticised, and I felt like I was permanently walking on eggshells. I'd get frustrated and cry sometimes and he'd tell me he wouldn't get mad if I could "just be a good girl, and don't make him mad".
One day I got frustrated when he was telling me off for not doing something he'd never asked me to do, and told him so. He flew into a rage and pushed me off my feet, yelling "Don't talk back to me!"
I'd hurt my back the way I landed and began to scream, whereupon he got down on the floor, held his hand over my mouth and nose so that I couldn't breathe, while hissing "Shut up! Shut up!" until I was weak and limp (although still conscious).
He put me in my room after that (I was too terrified to make a peep), and had a long talk with me about how (and this is probably my clearest childhood memory of all, it changed my life):
-he didn't want to do that, but I had been bad and needed to learn
-he wouldn't do it any more if I was good
-if I told Mum she would be angry with me for making him mad
-she might take me away from him so that I wouldn't make him mad any more
-he didn't want that to happen because he loved me and would miss me
and then he hugged me for a long time, stroking my hair, and telling me 'just be a good girl, ok.'
From then on, life was never the same. His rages escalated slowly but steadily (always followed by the same chat). He beat me regularly (to the extent I have internal organ injuries to this day), and continued to smother me if I screamed.
My Mum was suspicious from time to time, and would ask me if anything was happening. I didn't want her to get mad at him or me, and would always firmly deny it, and come up with some pretty good (imaginative) excuses.
Anyway, I'm so sorry, this turned into way more of a personal narrative than I meant it to be (all comes spilling out).
Suffice to say that by the time I left home I was a wreck, self-harming, suicidal attempts (none of which anyone ever knew about), and permanently anxious. I went on to have some nasty abusive relationships of my own before striking it lucky with current DH (who is wonderful).
I have no contact with my father (never want to see him again), and struggle with anger at my mother (for not knowing/stopping things), and with myself for never saying anything, and never being 'good enough'.
Although my mother knows everything now (things came out eventually through my younger siblings who were also abused), and has nothing to do with him, she maintains until she is blue in the face that she had no idea, that she would have left him immediately if she did, and that she knew he could be angry, but never violent.
I guess what I'm really trying to say is that you really will never know what goes on in the house when you're not there (because children are so easily manipulated to cover up), and someone who has form for physical violence (choking etc.) will almost inevitably repeat that behaviour.
I wish to god my mum had just left when she realised 'she' had to walk on eggshells around him or face anger. Because he expected just the same from us (children) as we grew older. And was able to manipulate us into accepting much worse.