"Don't spoil the magic" could mean do not look for the correct explanations or do not try to understand it seriously.
By the context you have given, maybe Chris was a magician. Perhaps someone full of joy who enjoyed life intensively, preferring to appreciate the beauty of the result a good magic trick rather than its logical explanation. But this is just a possible interpretation - still you need more context to be sure. And maybe it is the author's intention not to let it completely clear.