It depends how you measure contribution. If she has cooked and kept house, helped raise his children and put in a full effort to keep the details of life ticking over while he worked (and she may in fact have been in full-time paid employment, and payed her part of the mortgage, rates and household utilities as well) then that is a contribution. Too many people these days need to be able to put an explicit level of renumeration onto a task to assign it value.