Ji-li's mom seems very frail. Perhaps that's because she gets sick and faints a lot (diagnosis: Meniere's syndrome). Or maybe it's because she's really emotional—she worries a lot about her husband once he's arrested on false charges. Wouldn't you? Still, she stays the course for her kids. She might show her emotions much more than Ji-li, but that doesn't mean she's any weaker. She cares a lot about her family and wants them to be together again.
When Ji-li explains to us what life was like before the Cultural Revolution, she tells us that they eagerly awaited their mom coming home every night: "We rushed out to greet her and opened her handbag, where there was sure to be a treat for us. Mom spoiled us" (1.57). It's clear Ying-Chen loves her kids and lavishes them with warmth and affection. She encourages Ji-li to be strong and sets a solid example for her children about the importance of family and sticking together.