White Night isn't sure how to give her the news. It can be very tricky to handle the emotions of his autistic sister. In addition to delays in social skills, Nightlight can easily get distressed — leading to the occasional meltdown.
If you want to read more, you can see the full story outline (work in progress) on my Patreon page! Here is the table of contents: https://www.patreon.com/posts/43115929.