This will prevent Sinéad from sending you messages, friend request or from viewing your profile. They will not be notified. Comments on discussion boards from them will be hidden by default.
“you have to be the prude or the slut, and if you pick one, other people hate you for it, and you can’t trust anyone anymore, because they’re all after the same thing, and you see that you can never go back to how was before…”
―
Ned Vizzini