I think she probably is grieving.
A friend of mine whose dog refused to eat after the death of his companion, made a great display of spreading a piece of bread with tinned dog-food, then sat himself down at the table with knife and fork poised.
It worked, up trotted the grief-stricken dog and looked expectantly at his master, who pretended not to have seen dog, and pretended to eat with every sign of enjoyment. After a suitable time, he loudly said he was full-up, and rose, took his plate out into the kitchen and emptied the contents into the dog's bowl and the dog happily muched his food.
My cat ate his food all right after losing his brother, but abstained from hunting mice for nine solid weeks, during which time he didn't growl at intruding dogs either.
I knew he had come to terms with his brother's death when he sat in front of a pile of brushwood all day on a drizzly autumn day waiting for an unwary mouse, and when I later heard him chasing a dog to kingdom come!