I think context is important when discussing the sister's claims about shopping or guilt. This is a grieving sister who is trying to make the point that this wasn't suicide and she is doing so by attempting to make it seem as if Rebecca was not in a suicidal state of mind. I don't deny that such claims can, in turn, make her appear callous, but let's consider the source and what her point is. Her point is not that Rebecca was some sort of uncaring individual, her point was she was not suicidal. Again, I get that these claims can be extrapolated into, Rebecca didn't care about Max. But that's not her intention and I'm sure in her grief she never thought of it that way. Not to mention, as others have said, we don't know why or where or for what she went shopping.