A supernova happens when a huge star runs out of fuel. Entire galaxies can be outshined by one stars death.
The word supernova in this context however means when someone finally gives up and ends
something and
the person on the receiving end of this breakup’s whole world may collapse when the end came. Examples may be a loved one dying and you experiencing a ‘supernova’ because your whole universe has been outshined by one person
running out of fuel. Other examples may be with breakups or missed opportunities.