Ever since Judy Syfers wrote "Why I Want a Wife" in 1971, people have been using the word "wife" to refer to non-spouses who perform traditional "wifely" chores, like cleaning. The latest culprit: a service called The Occasional Wife.
Occasional Wife founder Kay Morrison writes, "The Occasional Wife is a concept born in my kitchen [sounds messy] during a morning discussion with my husband. It was one of those days when neither our schedules nor our two young children were cooperating. At that point we realized that this family, our family, needed a 'wife.'"
Sociological Images makes a great commentary... http://contexts.org/socimages/2009/06/23/wouldnt-a-wife-be-great/