This trophy seems to require you to be friendly with Matkina by the end of the game and to have acted with compassion in her presence instead of reaffirming her vengeful habits.
Then, in the end when the Sorrow asks you what you want to do you have to decide that none of his options are good and that you will instead destroy him.
When the Matkina's ending slide appears the trophy should pop.
This was actually my last trophy because no matter what I tried and eventhough her affection for the main character was high she would always get the other ending screen saying she became Memovira.
I had to revert back to an older save and only acted nice in her presence, and that solved it.