"Every time you see them happy you remember how sad they're going to be. And it breaks your heart. Because what's the point in them being happy now if they're going to be sad later? The answer is, of course, because they are going to be sad later.
Why the Doctor didn't come back for Amy for 12 years - the whole course of history would change if he had been on time! HIS personal destiny would have changed if he had been on time! If Mels were to succeed in killing him at her younger age, then Rory an