My aunt's husband is my uncle.
My wife's nephew is my nephew.
Is my nephew's wife my niece? And does it matter whether this is "my" nephew or my wife's nephew (i.e. whether we're blood relatives), i.e. would she actually be my niece-in-law once removed?
It seems logical for these things to be symmetrical, i.e. I can only be someone's uncle if he/she is also my nephew/niece (and vice-versa), but it seems a bit strange that the marriage link is only implicit in one direction. Maybe it's just that this is a relationship that typically starts at birth, so it's unusual for it to come later (if the uncle or nephew gets married).