What is the different between wife and girl friend

GOOD QUESTION BUDDY...WELL GIRLFRND IS NOT WIFE AND WIFE IS NOT GIRLFRND...GOT IT?????....NO ....LET ME EXPLAIN GIRLFRND IS SHE WHO CAN LEAVE U IN FUTURE AND HAS NO RELATION WITH U AT ANY MOMENT OF LIFE IN FURTHER...AND A WIFE IS SHE EVEN AFTER SHE LEAVES YOU STILL SHE IS CONTINUED TO BE CALLED AS Mrs. XYZ..A GIRL FRND CANT BE CALLED UR WIFE UNTIL AND UNLESS U ARE MARRIED TO HER