I think her feeling like crying suddenly is a fact of the character she's stuck in that wasn't revealed in the books, much like how Gracy married Cesar to be able to do what she wants since she can't inherit (being a woman). Often times writers have more background on their characters in their stories that are never revealed because it just never comes up/isn't important enough.
If when the MC read the book her character she's stuck as now couldn't have children to begin with but it was never mentioned, she wouldn't know that fact but the character itself would so when her d***he brother mentioned that maybe she can't have kids her character gave a natural reaction to the fact that the MC would not originally have known to begin with.
I think her feeling like crying suddenly is a fact of the character she's stuck in that wasn't revealed in the books, much like how Gracy married Cesar to be able to do what she wants since she can't inherit (being a woman). Often times writers have more background on their characters in their stories that are never revealed because it just never comes up/isn't important enough.
If when the MC read the book her character she's stuck as now couldn't have children to begin with but it was never mentioned, she wouldn't know that fact but the character itself would so when her d***he brother mentioned that maybe she can't have kids her character gave a natural reaction to the fact that the MC would not originally have known to begin with.