Missing person - can anyone help?

[trebor2]

I am trying to discover what happened to a Henry Mcadie who was born in Wick, Caithness, Scotland in 1855. He appears twice on the 1881 census - once in Wick with his family and also in Inverness with his wife. Shortly after this date, his wife was admitted to a lunatic asylum in Inverness and appears on the 1891 (and possibly on the 1901 census also) but her husband Henry does not. And can find no death certificate and no mention of emmigration. Can anyone offer any suggestions or advice. I would very much appreciate any help solving this puzzle.
Regards,
Rob Macadie