Did it ever explain why they chose to hide it? Like i see no reason why they would

From what I remember it's not like they're hiding it (MC said so to her library friend), it's more about her wanting to tell her friends personally but she can't seem to find the right timing cuz her friends keep saying she's an angel or that she's too innocent. I think by now she got too used to "hiding" it so it may take a stronger push to come out clean

It's kinda dumb in my opinion but it's the main reason for the struggle