My frist thought was Columbo as his wife was referred to but not seen in the series.
There was a series called Mrs Columbo ( and later Kate Loves A Mystery) strring Kate Mulgrew,which returned the favour.
i think it's minder, & me &my girl, the wife who was never seen was muriel yates wife of derek yates (played by tim brooke taylor) it also starred joan sanderson, richard O'sullivan, joanne ridley, leni harper,sandra clarke, joanne campbell