When Liu Yue'e spoke earlier, she was pressing them to agree. Refusal would amount to being ungrateful. But Aunt's deep bow and her begging posture showed that they were pressuring her, and that Aunt could only humbly beg for forgiveness.
This cleverly turned the reason and righteousness back in their favor. In the end, it was Grandfather who put a stop to the matter.
Su Xiaowan hadn't expected that her aunt would dare to confront her grandfather for her sake, or that she'd have the courage to stand up to everyone else. It was exceptionally hard for someone like her aunt, who traditionally views the husband as the sky and obedience to parents as a core virtue, to do such a thing.
At the same time, Su Xiaowan was also touched by her aunt's sacrifice. Her aunt had truly pushed past her limits for her. She was willing to start a physical confrontation on her behalf before, and now, she had even made enemies within her own family for her sake.