A Captain and a doctor walk into a bar.
They talk.
The doctor goes and the Captain realises two things; first, that the doctor to "repair" the universe in the doctor's views will always work to his mates death. Ianto's death.
Then he stands, exits and goes and succeedes on his way to bring his mate back. forever.
Second,
The future hasn't happened yet. Isn't set in stone.
...
the doctor works towards 'a future to his liking' . That doesn't mean it( future) should be like it( his formed and patched idea)!
Cause the future won't be how the doctor wants it!