"No, but you're so clever! Can't you bring her memory back? Just go to her now, go on, just run across the street, go up and say hello!" Wilf has the option of being soft because they are his children, he can hope against the Steel Age. But it's important too that he mentioned cleverness, because that's exactly the issue, and the Doctor knows that. Cleverness without love is not humanity, and neither is love without cleverness, and either way that's what going to Donna would be now. "If she ever remembers me, her mind will burn, and she will die." We forget because we must.
Outside, they can hear Donna yelling at the metermaid, adorably, and they laugh about how wonderful she is -- how much of her was always there. She's joined by her fiancé, Shaun Temple, and the Doctor is shocked that she'll be having yet another wedding -- and that her name will be "Noble-Temple." Wilf shakes his head and says it's going to be "Temple-Noble," which is scarcely better. Either way, the point is clear. She's the household goddess of temples across time. She is stronger than she knows. "Is she happy? Is he nice?" Shaun's sweet enough -- a bit of a dreamer, of course -- and on minimum wage. "She's earning tuppence, so all they can afford is a tiny little flat. And then sometimes I see this look on her face, like she's so sad. But she can't remember why." She's got him. She's making do. As are we all.
But often, in the world's most crowded streets,
But often, in the din of strife,
There rises an unspeakable desire
After the knowledge of our buried life;
A thirst to spend our fire and restless force
In tracking out our true, original course;
A longing to inquire
Into the mystery of this heart which beats
So wild, so deep in us, to know
Whence our lives come and where they go.
"How about you?" Wilf asks. "Who've you got, now?" He starts off brave -- "no one, traveling alone" -- but immediately goes dark and breaks down in front of Wilf, ashamed. "...I thought it was better. But I did some things, it went wrong. I need..." He begins to weep, and Wilf reaches out, horrified and compassionate, deadly worried for him. "Merry Christmas," the Doctor laughs, manning up and wiping his tears away; Wilf is weeping too. "But don't you see? You need her, Doctor. I mean, look, wouldn't she make you laugh again? Good old Donna?" The car pulls away, as the Doctor cries.