The only moment I can think of is the Much Music interview from around the end of May when Louis denied Larry and claimed that people think he and Harry are together because they sometimes put their arms around each other’s shoulders. And then he put his arm around Harry’s shoulders and Harry flinched (Harry was staring down at and fiddling with his bracelet). That is literally the only moment I know of.
And yes, body language like that is a giant clue. Other than that one moment, they always stay in close to each other or squeeze in even more. Including their faces. When they were in Dublin the year previously, Harry grabbed Zayn’s butt that day—he also pushed the mic at Zayn without even looking at him (he was in the middle of staring at Louis). When they went to speak into the mic, they kept on putting their faces close to each other before moving it back to the mic. Louis has acted touchy-feely with Liam; he’s also flinched away from him. Liam has dry humped Zayn; he also flinches away from him sometimes. And so on.
If I saw Louis and Harry pulling away from each other or shrugging each other off, I would think the situation was a lot different.