This will prevent B 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 get lonely, is what it is. A person's not supposed to go through life with absolutely nobody. It's not normal. The longer you go by yourself the weirder you get, and the weirder you get the longer you go by yourself. It's a loop and you gotta do something to get out of it.”
―
Jim Shepard