Sherlock likes to travel, John doesn't.
"Please, John. Just for a few days."
"No. I don't want to go to Paris. I've traveled enough for my lifetime."
"But there's a nice murder to solve."
"Sweetie, I don't want to go to Paris. And I certainly don't want to go to Paris to solve a murder."
"But you like murders."
"I like you, and that's not making me want to go to Paris any more than I wanted to five minutes ago."
"Oh, pleasant, you like me today."
"I like you every day."
"Then, come to Paris with me."
"No."
The next morning, Sherlock was rushing around their bedroom while packing for Paris, which he was to leave for in one hour.
"How long will you be gone?"
"A few days. Five, probably."
"Five is more than a few."
"It's not too late to come with me."
"No."
"Then, stop complaining." Sherlock leaned over John and gave him a quick kiss before pulling papers off the bedside table.
"What time are you leaving?"
"Mycroft will be here in one hour."
"Just enough time to…" John's voice trailed off as he swung his legs over the side of the bed, sat up, and pulled Sherlock between his legs.
"No, no. I've got to go. I need to get ready and-"
"Why are you never this excited when I want to do something?"
"You weren't excited when I told you about Paris."
"All right, good point." John wrapped his arms around Sherlock's waist and kissed his neck.
"I have to go."
"I'm not holding you here." John licked Sherlock's neck. "How is it that even when I know you haven't bathed in about three days, you still manage to taste delicious?"
"Because you're horny."
"If you lived with you, you would be too." John's licks traveled down to Sherlock's chest, then back up to his throat.
"Fine, fine. But make it quick." Sherlock pushed John onto the bed and straddled his legs.
Six days later, and not much contact since he left, Sherlock was exiting Mycroft's car at 221B. It was the middle of the afternoon, so Sherlock knew John was at work. He got in the house and found a note that read:
"Sherlock, I'll pick up dinner on the way home. I missed you, don't leave again."
Sherlock smiled and stuck the note in his pocket, then waited and waited and waited for John to get home.
John came home two hours later, and Sherlock could hear him racing up the stairs.
"Sherlock, Sherlock are you home yet?"
John barely had the door open before Sherlock's tongue was nearly at his throat. John was caught off guard at first, but in seconds he dropped the food and wrapped his arms tight around Sherlock's waist, puling him closer and making Sherlock push him against the door. They stayed like that for a minute, maybe five, alright, ten, and finally John pulled away and spoke.
"Don't leave again, alright?"
"But I solved the case, John. It was perfect. Brilliant, just brilliant."
"No, I don't want you to leave again. I missed you too much and-"
Sherlock cut him off by kissing him again. Sherlock would never, ever get used to being missed, something he'd never felt before in his life.
The next time Sherlock decided they needed to travel, they did. John huffed and gave Sherlock the silent treatment for nearly a whole day, but that was better than being apart, with minimal contact, for six.