The second daughter of Elder Rose was only two years younger than Gabriel and because only a handful of people, who knew about her existence, thus when Rei didn't return the second baby, no one made a fuss. There was no rumor about it as well, everyone involved, sealed their mouth and said nothing about this matter.
And for Elder Rose, it seemed, what happened to her second baby left a huge trauma on her, since she couldn't confide this matter to anyone and she had to swallow her bitterness and grievances of losing her baby alone, especially when this baby was conceived out of love, not duty.
A mother, who lost their baby would understand what kind of hell that Elder Rose had to go through alone, therefore when she was being pregnant again in her not so young age, she detached herself from the baby instinctively, afraid the same thing happened again.