There was a line he said towards the end of the episode " I remember each time ".
I wonder what that meant.
I took a look at the script to find the section, and I believe he's referring to remembering every time he loses a companion, because he's having trouble dealing with the loss of Clara and wants to give up entirely, and thinks it's futile to carry on when nothing he does will bring her back. He's overcome with grief.
THE DOCTOR
I can’t keep doing this. I can’t
always do this, it’s not fair! Just
this once, can’t I give in? Can’t I
lose??
He spins round on Clara -
- still standing with her back to him. But chalked on the
blackboard in front of her, a single word:
No!
The Doctor, staring hopelessly at that word.
THE DOCTOR (cont’d)
But I can remember, Clara. You
don’t understand, I can remember it
all. Every time!
Just the word No!
THE DOCTOR (cont’d)
And you’re still gone. Whatever I
do, you still won’t be here.
The Doctor sags. Like that admission ripped the heart out of
him.
And then, impossibly - her voice.
CLARA
Doctor.
He startles, looks at her. What?
And magically, impossibly -
- she turns to face him. Clara Oswald, fixing him in the eye.
CLARA (cont’d)
Stop it. Just stop.
He stares at her.
CLARA (cont’d)
You’re not the only person who ever
lost someone. It’s the story of
everybody. Get over it. Beat it.
Break free.
She steps towards him, puts a hand to his face.
CLARA (cont’d)
Doctor, it’s time. Get up off your
arse ... and win!