“Ooh the posh boy loves the dominatrix.” John’s subconscious is goading him in the form of MARY, the woman he chose to “move on” from Sherlock with. And John is so jealous of the possibility of Sherlock and Irene being together that he doesn’t even consider Sherlock falling in love with him. But, he loves Sherlock so much that he ENCOURAGES Sherlock to text Irene back, because he wants Sherlock to be HAPPY. He doesn’t want him to regret leaving things unsaid. And Sherlock is so focussed on John crying and comforting him, he feels it’s not the right moment to Say Things. Not yet. Romantic miscommunication at its finest.