This is probably because they don't play games and are just doing their things. I don't feel from their content like they need to prove the world anything, like the other couples, so even if they spend a lot of time together and they show it, they feel natural.The only ones who ever look normal in the paddock to me are Valtteri and Tiffany!
(and to me those over the top ones are more annoying than those who seem "distant" because they at least don't put everything on social media)