Sorry, the Wenders film is called 'Everything will be Fine' (it's not a great film, though beautifully shot).
Back to Gadon and Franco, I think they are the most romantic, best matching couple in a King adaptation since Bonnie Bedelia/David Soul in Salem's Lot.
I was actually thinking what makes an actor/person feel 'detached' or 'distant' to me, but I think it comes down to a lack of warmth. It's not that a 'detached' person can't be nice or friendly, Gadon or Franco seem friendly to me, but it's like you connect less to them, like they're more isolated. It's hard to pinpoint what exactly causes this (in general it's hard to say what draws you to certain people and makes you keep your distance from others).
For example, as beautiful as Gadon is, I don't think of her in terms of sexy (and most beautiful actresses I find sexy too). And when you find someone sexy you call them 'hot', so it has to do with warmth. It's the same with a lot of super-models, I find them the opposite of 'hot', they're like utterly perfect statues almost. But for a Cronenberg film it's perfect.