Talk to me about pre-kerberos Sheith being that touchy feely couple. They were always touching. Hand holding, arm around shoulder/waist, ankles curled around each other under the table, etc.
Now think about how that changed after everything Shiro went through. Keith being scared of trigger Shiro by touching him the wrong way and even being afraid that he doesn’t remember what they were together. Shiro being afraid that Keith wouldn’t want him anymore after everything and being afraid to touch him with the Arm.
So they start small, the same way they started their relationship the first time. It all starts with the shoulder touches. They were brief at first, but then they started to linger. Shoulder touches turn into hand touches. Linking their pinkies together when they’re standing next to each other. Shiro has places that he doesn’t like to be touched anymore, even through the thick paladin armor. Keith is a bit jumpier than he used to be, especially after a battle. They learn to navigate these changes and relearn everything about each other down to the smallest things.