Trying to explain something to someone and no matter how well or how much you explain they just don't get it or refuse to get it.
"All the evidence shows there was no election fraud but trump supporters still won't believe, you can lead a fuckwit to logic but you can't make them think"
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.