You had known from the very start that the woman on the table had not been Irene Adler. You knew every contour, ever line, every strand of hair on her body. You had thought about her, every waking minute. It is not in your nature to mistake, or lie. And yet, you did. It is the first time since Redbeard, that you ever lost control over your tongue. You could have, of course, rectified your error immediately. But you didn't. It was very obvious Irene Adler faked her death to escape something, and did not have a lot of friends. By identifying her body, you would have aided the escape. She would drop in to thank you personally, someday.
You had looked forward to that.
Of course, the game had changed entirely from then. You remembered, with a faint tinge of bitterness, how you had nearly been outsmarted. Looking back, her guarded eyes should have warned you. But they didn't. Now that you think of it, out of all the times she had been with you, only once had she let down the shield. In Karachi. You had seen it then, the raw fear. The crippling sense of doom.
The only time you had witnessed the real Irene Adler, was when you had stepped in to kill her.
You had a feeling this would be a defining moment in your relationship.