Plenty of actors and actresses fake romantic relationships with others despite having other romantic relationships in real life, but pretending someone is one’s wife and making love to them is a whole other ballgame than pretending someone is one’s sister and making love to them, so point taken from Mr. Coster-Waldau.
The positive takeaway here is that the Game Of Thrones star didn’t giggle skeezily while implying he’s 100% cool with the subtext of those bumped uglies.
It appears the taboo nature of the topic troubles Nikolaj Coster-Waldau more than anything.