It's not her responsibility to do anything for him, and he doesn't want to put that kind of burden on her. It's a lot to cope with, even as someone who's more desensitized to how awful it really is, so of course it would be way too heavy to put on someone who wasn't expecting it. After all, if that wasn't the case, she definitely wouldn't sound so small and unsure right now, even though that had been only a small slice of the big picture.

But now she has seen it, and there's no way he can take that back, as sick as that makes him feel. She's using it as an opportunity to try and comfort him, rather than voice any questions something like that would have undoubtedly raised, or act particularly horrified. Either of those would make more sense, as far as he's concerned, and maybe she'd feel differently if she got more information about it, but, no. For now, she opts for this incredibly gentle approach, and Shinji's still pretty lost on how exactly to handle it.

"It's okay," he repeats, just as small but less unsteady as before. There's a brief moment where he hesitates with what to say, but relaxes his stance enough to slowly shift from simply resting his hands at her back to a more complete, more meaningful hug. "You're doing just fine, you've been doing just fine. I promise."