He watched as the plane took off in front of him. As it disappeared to Eastern Europe or wherever it was Mycroft had sent Sherlock off to, John sighed and felt Mary put her hand on his back.
"Hey" she said softly in his ear.
"Hey" he said back, still watching the plane disappear into the distance. He tried to swallow but realised he had a lump in his throat. He pursed his lips together and took a deep breath. He didn't move. He wanted to watch the plane until it was a dot, until it disappeared.
It had been a strange goodbye. Very different to the last one. Neither had been planned, but he'd had time to prepare for this one. The events of the last few days swam in front of John's eyes. Magnussen's shooting. Sherlock, shooting him in the head right in front of everyone. He'd done that for John. Well, he'd done that for John and Mary. And the baby.
But the idea that Sherlock could do something for someone else...could be selfless...John didn't know what had gone on in those two years Sherlock had supposedly been dead, but he'd come back with the ability to love people. He clearly adored Mary.
John felt Mary take his hand and pull him towards the waiting car. The plane had long since disappeared into the sky.
"Can you...give me a minute?" he asked her. She nodded and got into the car. John took a few steps away, towards where the plane containing his best friend, one of the two people he loved the most, had disappeared over the horizon.
"Thank you, Sherlock" he said softly. He closed his eyes and to no-one, in his heart of hearts, inside the middle of his soul he quietly said to himself "I love you, Sherlock Holmes, you terrible, amazing man. I will never, ever forget you."
He opened his eyes, turned and walked towards the car and his new family.