SPOILERS: I loved this part (you know, besides the whole reason why this convo is taking place ) Sherlock is being Watson's best friend, he's being honest, he's comforting John (kind of), and John is looking to his best friend for answers.
"We're laughing but we're also dead inside." The most true statement ever. Everyone i meet is always like "only three episodes a season?" And i'm like "Yes, each 90 mins long and heart wrenching at the end of a season.