What if Tom wasn’t in the picture and Molly was never engaged. These scene could have been different.
Molly: “What was this day about?”
Sherlock: “Saying thank you.”
Molly: “For what?”
Sherlock: For what you did for me.
Molly: It’s okay, it was my pleasure.
Sherlock: No, I mean it.
Molly: Well, when I said pleasure I mean …
Sherlock: Moriarty slipped up, he made a mistake. Because the one person he thought didn’t matter at all to me, was the one person who mattered the most. You made it all possible. And I hope we could do this again anytime soon.
Molly: I love the day. I really did, it’s just, well, when we were down in that old cellar you called me John. I thought you wanted me to be myself.
Sherlock: I’m sorry that I’ve called you that. You know how much I’m used to John being with me when we do investigations together. Forgive me.
Molly: It’s okay. I know you missed him.
Sherlock: But I’m glad you came with me today.
Molly: Like I said, it’s my pleasure.
Sherlock: So, let’s get some chips shall we.
Molly: Love to.