noun, noun or participle which takes 'suru', transitive verb
treating like a stranger; cold-shouldering
Used when someone is treated as an outsider or ignored, often in a context where closeness is expected.
長年連れ添った妻に他人扱いされた。
I was treated like a stranger by my wife of many years.
親友を他人扱いする
It's cruel to treat your best friend like a stranger.