The gift of men, Tolkien's immortal elves call it: death.
The one thing that can make people finally clean out the utility drawer, give away an impossible accumulation of sewing materials, and get rid of the 1967 - 1973 Scientific American magazines.
The thing that finally breaks all wedding vows. The thing that clears the way for creatures that are young, clean-limbed, and fresh to imagine (in their turn) that they will always be so. The thing that makes room.
My mother died last winter. Ours was a relationship of deep mutual disappointment and bright superficial cheer: we managed to wound each other and fail each other remarkably often, for people who saw each other so little. The one thing we each wanted of the other was the one thing we could not give: a respectful understanding.
No parent-child relationship is ever actually over, I suppose, but the death of one party marks it, like a visa stamp on a passport.
I am free to travel, now. I'm sorry. I'll carry my failure forever: but it will be localized now: a dead zone in an otherwise living sea.
And maybe I will even clear out a few boxes and throw a few things away, ahead of time. She would approve of that.