I was preparing my post at the when yours was posted. You said it better than I did of course.

It's interesting what you say about arms length. I wonder if it would be awkward for them, knowing they're attracted to eachother, to use first names even though they're now family. Perhaps it would have seemed too intimate to them. And maybe they're avoiding calling each other by name altogether. Edward and Marianne were using each other's names quite liberally in that conversation.