I believe the killing of the dog Diego negatively changed things for Tara. Of all the abuse Shawn did to her, mentally or physically, I believe this one was the worst. She used to be scared to get close to him or even just be in the same room with him because she fears he would pin her down, put her head in the toilet, or twist her wrist, but now, her fear of pain took a turn. She now fears for her life.