It dawns on Grace in a way that surprises her. Peter is bending down to pick up a toy Ivy dropped on the grass. He hands Matilda the toy. She observes how hard it is for him to straighten up. Is it his spine? Or his knees?
Grace is standing at the sink rinsing out Ivy's drink bottle after it fell too close to some dog shit (it now makes sense why Peter hadn't picked it up). The realisation that her husband is getting old hits her hard. And in the fading light of the afternoon, she can see a slither of her own reflection in the window and knows that she, too, is getting old.
So much of what she could once do, she simply can't do anymore. Memories of watching her own mother get old fills her with dread. Watching her mourn the loss of her second husband now seems unbearably real. How can she expect to suffer through the loss of Peter?
She turns to the empty room and imagines the mornings without him, without the sounds he makes as he seats himself, or the way his presence fills a room, or the feel of his weight in the bed at night.
A squeal of delight from Ivy turns her around again. And she sees it, the conveyor belt of life. Her mother slipped off it some years ago, and now it'll be her turn next. Down the other end, she sees Ivy's life spread before her. No, that's not true. She can't see any of that. Just like she didn't see Matilda's life, nor Rory's.
What she can see is her and Peter's life. They'll need to start making adjustments, such as railings in the shower and toilet, and non-stick surfaces where the water pools on the front steps. Eventually, they'll need to think about a ramp up the three front steps.
The end of the conveyor belt is as tricky as the beginning, only you don't have someone to watch over you, or to teach you how to make a dignified exit.