I think it depends on how well she trusted him, his routine his schedule was, how her work schedule was, and (if they were broken up) how amicable the break up was.
I can imagine a man, who worked long hours, not communicate with the mother for a week so I can also imagine a woman who worked long hours, as KB was known to, not communicate for a week. I’m a woman in my 20s and people in my peer group who are working mothers get very busy. It happens.
Also, some break ups are the opposite of amicable. They may have only communicated about “pick ups and drop offs” for the child. I’ve known of some parents who’ve had divorces that only communicate to each other through a lawyer basic things about their child. I had a childhood friend whose divorced parents only communicated to each other through a third party.