Young couple goes on van tour of US, boy comes back with van - no girl

Zaphod said

I expected this was how it’d go from the start. Nothing can take away their loss, but hopefully both families will be able to find some closure.

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I’m lucky that I’m not in a position to know, but what is ‘find closure’?
Is it possible with a tragic loss
I can’t remember how long ago MBS lost his brother, but I think it’s been awhile and it still seems raw
My wife’s family lost her father to a motorcycle accident decades ago, and the loss seems to have encoded itself into my MiL’s life
I’m not trying to be obtuse, but what is closure?