>> Odd thought : with the Emergency Transformation trope where someone converts a dying loved one into a robot, cyborg or AI, wouldn't this sort of issue come up as well? <<

It can be. I've only seen it addressed once, in Tanya Huff's Blood Ties. They had to split up because two vampires couldn't share the same territory.

>> ...and that's a fairly-common often-unnoticed part of sexuality and plain ol' platonic human bonding that people don't really think about it.<<

Modern humans go to long lengths to avoid smelling each other. This is not helpful.

>> So mightn't one possibly end up with a very dramatic shift in the relationship?<<

True.