Liberty wrote:
The "couple" speech is odd, but it clearly doesn't mean a couple in the sense of people in sexual relationship - we know that they're not. If it was just that John wanted to get together with Sherlock, then the truth would now be out there, and if Johnlock existed, Sherlock would now know John's intentions towards him. But nothing comes of it, so it's not that either.
Irene also revealed that she is totally gay in the "couple" speech. Maybe Sherlock is devastated because of that? 
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I cannot live without brainwork. What else is there to live for? Stand at the window there. Was there ever such a dreary, dismal, unprofitable world? See how the yellow fog swirls down the street and drifts across the dun-coloured houses. What could be more hopelessly prosaic and material? What is the use of having powers, Doctor, when one has no field upon which to exert them?
