In my opinion, it is fairly common for people to try too hard to mentally eradicate every ounce of masculinity... or rather, they tell themselves that everything they are and do is the essence of femininity and there is no icky masculinity mixed up in there.
That is of course just self-deception, and everyone, even if not biologically born male has some masculine traits. I think lying to oneself about that is pointless and personally like to take the more neutral view that it is a spectrum and I am somewhere in the female threshold.
Perhaps the subconscious element at play is that of, ironically, a repressed masculine side. Note, of course, that wanting to be feminine is not necessarily a feminine trait (how many women do this?), and neither is wanting to not be masculine. Transition blurs the line between what we are and what we want to be, and what we want to not be. And I think that can destroy a healthy balance that is typical of people who don't think about any of these things at all.
Maybe, going off on a limb here, the horror of that masculine side at having to live as a woman was the buried horror of it actually being kept under lock and key to protect the "100% femme" illusion, or the horror of once again pretending to be something that one wants to be, not what one is.
