[It's scary because of the moments when he remembers she's a human - after moments when distinctions evaporate because with her it doesn't matter - and the word is heavy enough with insidious connotations to wind him, despite how far he's come. Scary because he doesn't know what lies ahead of him.]
You have nothing to apologize for.
[But it would be scarier without her by his side. He knows what it's like to have loneliness crush him down smaller and smaller to the point where he feels like he doesn't exist anymore. He doesn't want her to know that feeling.
She has been there for him, in that dark place where all you want is something to hold onto, so he will be here for her.]
[action]
You have nothing to apologize for.
[But it would be scarier without her by his side. He knows what it's like to have loneliness crush him down smaller and smaller to the point where he feels like he doesn't exist anymore. He doesn't want her to know that feeling.
She has been there for him, in that dark place where all you want is something to hold onto, so he will be here for her.]