It had been two weeks since he had seen Katie with this new detective. During that time he had seen her often in the lab. The tension he had expected after New Year's Eve never came up. She was cheerful almost every day, smiled to him every now and then and did some work for him without contradiction. She was happy.
And he could not bear it. So much happiness and these feelings made him sick and even more so because he knew it wasn't because of him. He did not want to feel like that. He had to rebuild his wall and decided to stay away from it for the time being. After all, he still had Molly for important analyses.

Sherlock had just arrived at the rather inconspicuous house, situated in a suburb of London, when he climbed down the stairs and finally rang the bell. It was already evening and he knew that they were at home.
A short time later a smaller blond man opened the door and looked at the CD questioningly.

"Sherlock? Has something happened?"

"Hello, John. I need to speak to Mary. Is she in?"
And as if she was standing by the door, she came over.

"Sherlock? What's going on?" And she invited him in.

He followed her into the living room and then sat down on the couch. Mary pointed John out to leave the room with a look.

"So Sherlock, what's happened?" she asked and sat down next to him.

"It... uh... it's about Katie," he said calmly.

Mary slapped her hands in front of her face.
"Oh, my God, I knew it! You love her."

Sherlock looked at her with eyes wide open. Oh, man, she knew it. Of course she knew. He must have known she'd figure it out so fast.
"Mary, don't be silly. Me and love. Well, no, not really."

Mary looked at him sceptically and sighed.
"Oh, Sherlock, what is it, then?"

He wiped his hands across his face.
"It's just that she's seeing this new Detective Constable and I don't think he's right for her."

"But you are." It was less a question than a statement.

"No...Possibly... I, um... I don't know, Mary. And I don't know if she feels the same way. I mean, after new year's eve."

Mary expelled air vociferously.
"So you did!," she cried triumphantly. "But wait, what was New Year's Eve?" she asked curiously.

Sherlock rolled his eyes and continued in a casual tone.
"Oh, nothing more. We were just sitting together on the roof looking at the rockets. At some point she asked me why I was doing this and I answered that this was something you do for friends after all. After that she was different somehow and now she's seeing this Detective Reid and seems happy."

"Oh, Sherlock. She's only seeing this Detective because you hurt her. She loves you. And you should tell her!"

Sherlock looked at Mary with disbelief. Was she right? Did Katie have such feelings for him and had he hurt her because he considered them friends?
"Er, and what, exactly, should I tell her?"

"That you love her, you idiot!"
Startled, the two of them now turned in the direction from which the voice came.
It was John who now moved towards them. And when he already knew what Sherlock was about to say next, he went on.

"Sherlock. You and I both know only too well that I'm the romantic here and I know these things better than you." He winked at Mary, then turned back to his best friend.
"And I can also see that you feel something for Katie. Admittedly, I didn't really realise it until Christmas. So go and tell her, damn it, before it's too late!"

John was right. He did feel something for her. But was it love? After all, he had no idea what something like that felt like. And besides, did he want to tell her? Should he really get involved and let romantic entanglements into his life? He suddenly noticed a great uncertainty rising within himself and did not know how this conversation should continue. He had to end this as soon as possible.

"John, as you know, feelings and something like love are not for me.
And honestly, this was a stupid idea. Just forget it," he said and got up from the couch.

Mary was just about to call after him, but by then he was already out the door.

He walked the streets for a while, thinking about what Mary had told him. She loves you! At that thought, that comforting feeling spread through his body again and a smile adorned his face. But it vanished as soon as he thought that she was now more involved with this Detective Reid. And she really seemed to be happy these last few weeks. But did he really want to destroy her happiness because of that? After all, he had hurt her often enough already. And besides, he was not a person for something like feelings and relationships.
At some point he finally came to the conclusion that it was too late anyway. He had lost. And he had to find his way back to his former ME to get along with it. No more feelings, no more thoughts about her and no more desire to be close to her. After all, he was Sherlock Holmes, who thought feelings were a chemical defect on the losing side. And he was not a loser.