He brought himself back into the present.
"Oh. That couple over there? Alright." John stared over at them for a good long while, his eyes narrowed. He was finding this one difficult. There was mixed body language coming from both.
"They're not a couple yet. They're dating? It looks like new love because they wouldn't be that close in a pub if they had been committed to each other for any length of time - they would be more relaxed. The woman is more into the man than the man is into the woman. She keeps flicking her hair. He's not displaying signs of flirtation whatsoever. But he does maintain eye conta-"
John stopped, realising he was wrong. He'd missed the vital evidence. They had weddings rings.
With a sigh, John brought the drink up to his lips. He glanced at Sherlock over the rim of the glass. "I was wrong. They're bloody married."