Doctor John Watson is a good man. He is faithful and loyal and he cares about his wife very much.
And he tries, he really does. He tries to be a good husband; to hold their lives together.
He sees the damage their work can do to a relationship.
He sees Greg's marriage finally fail and watches him move out of their family home, leaving a bitter ex-wife and two children.
So John always comes home at the end of the night.
Back to their family home; to their bed; to his wife.
"I really should get back, Sherlock." John says, stepping into the taxi at New Scotland Yard.
John had left work early to meet Sherlock and Greg at the Yard to give official statements on a case they had recently wrapped up.
The whole affair had lasted much longer than it was supposed to and, before anybody realised it, it was 7am the following morning.
"Mary will be worried." John justified. "I really should go."
Sherlock nods, instructing the cab driver to stop at John's house first.
John opens the front door and frowns.
There are suitcases. Two of them. Packed.
"Are we going away?" he asks Mary, hanging his coat in the hall.
"They're yours." She looks at him, eyes low and face sad.
"It's for the best."