Anna wrapped her arms around his middle and gripped the back of his shirt. She wanted to explain how she felt. She wanted to tell him why it was harder for her to fight with him than anyone else. But none of that made much sense in her head, so she knew she'd say it wrong. She and Dean kind of suffered from the same sort of foot in mouth syndrome. Anna had the inability to appropriately express herself, which is usually what set Cas off. She was just worried that, with everything so rocky right now, if she fought with Dean, there was no way they would all stay together. Dean was the part of the relationship that felt solid, like the glue to the whole thing, the reason she was even there to begin with. It terrified her when they argued.