Why doesn't Wang Yaru agree that Xiao Fang lives at home?

Wang Yaru is selfish. The whole family can move back to Xiaolou. Except Xiao Fang and Wang Yaru, they are split-minded, sometimes dirty and sometimes principled. Wang Yaru disagrees that Xiao Fang's return to Wang Yaru is selfish. It comes from the TV series Desire directed by Xiaowei Lu, which takes place in a factory from the late 1960s to the late 1980s.