Bye-Bye Ponds?

[Admiral_Young]

^ Exactly what we're trying to point out.

 

[Skellington]

Wouldn't he just pop back into the tardis and go back to before they died?

The doctor would still be sad since he saw when they would die

Since he apparentally can't do that with the Brigadier, I don't see why he could with Amy or Rory.

He may have already done that with the Brig, as in Battlefield Seven exclaims that Lethbridge-Stewart (who he thinks is mortally wounded) was supposed to die in bed. With Eleven's phone conversation, though, he's told that the Brig had for a while been expecting him to turn up but (crucially) that he never had.