We all know Rebecca already sees herself as the bad guy, and that Jack was the good guy in the family, but that doesn't mean she can ignore these serious problems. Of course, teenage Randall calling her out by saying she just doesn't care is grossly unfair, though probably in keeping to how a teenager would handle something like this. And to his credit, he does apologize later, and Rebecca confesses to him how much of a struggle it is for her just to get out of bed every morning. It's not an excuse, but she can't help it — she's grieving, too, and everything is so hard right now.