Headcanon that Sherlock is still an insecure bab when he and John get together but he never says anything to John. He doesn’t have to because John can see it in his face so John always makes sure that Sherlock knows that John loves him. Even though the smol pretends not to care because he’s under the impression that he’s extremely cool and untouchable (he’s actually screaming internally right now, his heart has turned into a marshmallowy mess with weird glowing bunnies and origami napkins in it)