Elennora was convinced when he thought that only a few people knew the truth about his gender. From Bianca's explanation, he learned that only four people knew that he was a man, not a woman, and those four people were Bianca, his parents, and the doctor who helped his mother give birth to him eighteen years ago.
Bianca gave no further details about the doctor, so he assumed that the doctor might have been threatened by his parents so that he would keep his mouth shut. Even Bianca was also controlled by his parents for so many years, and that was why he assumed that it wouldn't be a problem for his parents to force the doctor to shut up as well.
With that in mind, Elennora was sure that his secret was safe, at least for now. It was only today that he learned the truth that three more people knew that he was just a boy pretending to be a girl, and he didn't even know how to react after finding out the truth.
