One theory is that traumatic memories are not consolidated properly.
Meaning that they are not properly processed through the hippocampuss (usually as we sleep) to form connections with our cortex and become integrated into the rest of our knowledge and experiences
And so instead of being broken into their component parts and shelved away like with like--- images with images, words with words, emotions with emotions
They stay live in our hippocampuss, glued to our amygdales and other highly emotional parts of our midbrain
Leaving us with easily triggered flashbacks and continued grief
Until, in the normal brain, they are sllooooooowly integrated
So maybe before they are integrated it is hard to talk about them because they have not yet been digested: They're just sitting whole in our nonverbal emotional brains.
Here is an article called Traumatic Memory is Special
I have been through traumatic experiences which have left me speechless. Yet, I have stood firm through each difficulty due to the power of the faith in Jesus Christ.
I found this from the Bible helped me through traumatic times:
Proverbs 46:1-3 “God is our refuge and strength, an ever-present help in trouble. Therefore we will not fear, though the earth give way and the mountains fall into the heart of the sea, though its waters roar and foam and the mountains quake with their surging." (NIV)Isa 43:2-3 “When you go through deep waters, I will be with you. When you go through rivers of difficulty, you will not drown. When you walk through the fire of oppression, you will not be burned up; the flames will not consume you. For I am the Lord, your God.” (NIV)
The GOD of all existence is my God, and He has promised to fill me with his victorious Spirit, which cannot fail, cannot be conquered, cannot be destroyed. Although I may have been surrounded by chaos, and though my lips may have been sealed, my lungs was full of the breath of Life, and I continued on in His Holy name.