Friends are lost forever more unless he goes to Trenzalore.

Whisper Men

Sorry, mam, so sorry. I think I've been murdered.

Jenny

Clara: So you were a friend?
River: A little more than a friend.

Time travel has always been possible in dreams.

Madame Vastra

I don't know where I am. It's like I'm breaking into a million different pieces and there's only one thing I remember. I have to save The Doctor. He always looks different. Sometimes, I think I'm everywhere at once, running every second, just to save him. Doctor? But he never hears me. Almost never. Having blown into this world on a leaf, I'm still blowing. I don't think I'll ever learn. I'm Clara Oswald. I'm the Impossible Girl. I was born to save The Doctor.

Clara

Doctor Who Season 7 Episode 14 Quotes

River: How are you even doing that? I'm not really here.
The Doctor: You're always here to me. And I always listen. And I can always see you.
River: Then why didn't you speak to me?
The Doctor: Because I thought it would hurt too much.
River: I believe I could have coped.
The Doctor: No, I thought it would hurt me. And I was right. {Kisses} Since nobody else in this room can see you, God knows how that looked.

Time travel has always been possible in dreams.

Madame Vastra