What business is it of yours?

If I love you, what business is it of yours ? (Johann Wolfgang von Goethe)

I came across this quote today, when I was reading, The Dark Forest by Liu Cixin. It's an amazing book.

The quote is pretty simple, and yet pretty profound. It felt Stoic to me in that, one is mentioning about doing what's in their control, and which is not affecting another person. I believe there is some more context to this quote, which might make it anti-Stoic, but I don't know that yet.

In the book, this quote was followed by another quote:

If I destroy you, what business is it of yours ?

This quote felt like a threat, a threat filled with grandeur, the threat of which one can't escape, and yet it makes one feels worthy of being threatened.

EDIT: And there is some discussion on Reddit.