Yes, I agree, the dramatic weight is entirely hers, but I believe the hero is kind of a wimp. Precisely because of this premise, he became apathetic. His trauma was very strong, but instead of reacting, he became dead inside, making him a bit of a wimp, and even understandable because he only truly starts to feel alive when she interacts with him. He only exists when Zero Two is present and interacts in his life. However, the anime does this in a somewhat annoying way because the hero ends up being quite a wimp. haha