a middle-aged worker
熟年者｜〔総称〕the middle-aged; 〔初老の〕those who are past their prime
熟年離婚｜(a) gray divorce; (a) divorce late(r) in life; (a) middle-age divorce
He was divorced late in life.／He got a divorce when he was middle-aged.
「Gray divorce[The number of gray divorces] is on the rise.