Reinvestment profits from the sale of an apartment in the usual residence

Reinvesting in a primary residence is considered allocating part of the proceeds from the sale of a home to pay off the mortgage that is weighing on the primary residence. My primary residence is 100%, but I am going to contribute 50% to my wife as she has been helping pay the mortgage over the years. Do I have to make the donation before the home is sold so that she also benefits by removing the mortgage?