The reason why I think Tanjiro sees Giyuu as his older brother is because after his father died he had to be the man of the house taking care of everyone so when Giyuu acted like his older brother to him he really just felt more like a child.
Oh yes, Henry's wife, about whom we know nothing, as well as about William's wife, but the gacha channels know who they were, what they looked like and what they were like