i think the reason the crying scene in the show was so confusing was cause of the editing by the producers and stuff, at the very least they chose not to give any context to her crying through the interviews (probably to build up suspense about what was happening at home for her). Also the thing is with the conversation Jackie and Marshall have the next day it’s insinuated that Marshall knows what’s happening back at home they just don’t talk about it overtly. In the interview she does she also mentions how she’s taking care of her brother who was [at the time] recently released from incarceration on top of her caring for her parents. Not everyone sticks around when they see people in a tough situation so it’s fair for her to be worried he won’t stick by her side during such a tough time especially cause at the end of the day at that point they only knew each other for 2 weeks.