I'm really still wondering...
Spoiler
Show
Future Amy wanted to go with them, then leave the Tardis and go traveling. Why couldn't the doctor take her for a few minutes, and drop her off somewhere? It's been shown that the Tardis can take several Amy Ponds at a time before, in that short special. A couple of minutes, drop her off at some space port, or vacation planet, or adventuring location...
Would that have been so difficult?
And yes, I see it as the Doctor failing to save her. Or save Amy before she became that person in the first place.