when you put a book in the oven at 3 am and it catches fire and the whole house is burning down and your family is dying and your mom's last word was 'this is why I should've aborted you' and you get to heaven and meet god and he says 'I regret inventing the earth'
When some resigns or retires from a job, they are on "eternity leave". This can also refer to someone who has passed away, especially someone who worked somewhere for a long time, retired/resigned, then passed away later.
Oh I'm sorry, you didn't know that Kelly is on eternity leave? She resigned and moved to Hawaii!
With regrets I would like to inform you that my boss is officially on eternity leave. I will never see or hear them again. Ever.