Jawn, I agree with amethist.
Remember you don't know where she put the photo (don't ask)- it could be in her purse, for all you know, or at work, or in her car. It actually is probably a better way for her to tackle this; if she has an 'expectation' to heal quickly and it doesn't happen, she might feel you are just better off without her. She is trying to learn a new way of living/ thinking, but I'm sure she doesn't feel at all like herself. It will help her to not feel like she is letting you down, as well. The 'snacks' mean more (because they are in the present).
Just a thought- (it's possible), for all you know, the picture has some 'negative' thoughts/ triggers' behind it for her- not because it's a picture of the 2 of you but because she (may) remember feeling badly before it was taken, or after, etc. PTSD triggers are very wierd! (It's also something she would not have been likely to share with you, if you loved the picture, and because she keeps/ has kept things to herself).
What I'm saying (far too long) is have hope, I would not get discouraged. Remember, there are many possible explanations. Follow her lead, the present counts more.
Hugs and prayers-