Sounds like he has self doubt, deals with internalized toxic shame as a result of the trauma.
It can be hard, because essentially all this is seen through a lense that is this heavy self directed shame, that at times is projected unto others. Not like narcissists (not meant to harm, not meant to deflect or manipulate) but because they had a small otherwise healthy characteristic turn into a large overpowering force which they see themselves through.
Therapy can help with this for him.
So I stress that he can be helped, but he has to choose a route that *is help*, and this is his path meaning he will have to almost uncharacteristically choose to see past that filter if you choose to discuss this with him. Anyone who chooses to discuss this with him may be seen as "shaming him even more so then usual".
I say this because its very hard to get someone like this to see *convo that means I care about us/our relationship* as "non shaming*, when he already sees things through eyes that say *people are shaming me*, period. It can also turn serious conversations, into convos between you and this *wall of shame*, instead of *the him that you love*.
Yes you can become this ideal partner, learn non violent communication, take meds yourself so you don't act triggered/get reactive, follow rules for communication by those who specialize in attachment theory but ultimately this *issue of his*, will make it all be seen through that filter, and that filter is so heavy- it becomes like a self fulfilling prophecy for those who don't go get help for it(on his end and side).
It doesn't make him a bad person but it's super hard because it becomes a relationship with that, "wall of shame ", rather then the person you loved.