[Then that stare was replaced by a rather surprised look.] Your planet was destroyed?

There's many of variations of the story, as well as different reasons but the most popular version explains that the two lovers couldn't finish their work due to being so distracted with each other so they separated them with some kind of 'heaven river'. If you know what the Milky Way is, that's the river they were specifically talking about. [Coming from a folklorist family has it perks.]