Talk:Princess Cadance/@comment-24459886-20140628220147/@comment-24908786-20140702125524

Well, Celestia was more concerned about Chrysalis' threat against Canterlot, and when she retired for the night while Luna took over lookout duty, she pretty much felt that the threat at that point was a fake. Once that happened, she pretty much focused on her duties now presiding over the wedding, and when Twilight tried to expose Chrysalis without evidence to back her claim, Celestia was easily tricked by Chrysalis' sympathy act.

So Celestia was so busy, she never had a chance to notice something was wrong with her adopted niece, and Twilight never went to talk to her about her concerns so Celestia would have been suspicious as well, even before the rehearsal.