Perhaps what disturbs Clara more is not the Doctors actions but his cavalier attitude. He is dismissive of the concerns of those less knowledgeable than he is and patronizing when objections are given voice. Its understandable that Clara is confused as he simultaneously pushes her to grow up while treating her like a little girl. Hes not patient. He is, however, there when you really need him. This Doctor is a realist. If theres no way to save someone he doesnt bother trying. That doesnt mean that he wont attempt to keep everyone alive but he accepts that death is a part of life and its going to happen no matter what he does. The Doctor has never abandoned Clara though he has no qualms with waiting until the last minute to show up. Claras faith in the Doctor wavered but he was steadfast in his belief she would do the right thing.