I’m thinking that it is an old couple (hair, old, long), with flashbacks to their younger days?
Maybe they are not in love and maybe they never really were.
but they remain.
or maybe he loves her more than she ever loved him
It sounds content. Like, maybe they weren’t in love at first, they only stayed together for the family, but as time wore on they became attached to each other. Now they’ve grown old and face death together, but with no fear.
There’s a lot of allusions to aging here:
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