Get a ring for your lover,attach a note to it "Will you marry me?" and keep the ring in your purse or a bag. Tell some of his friend to take him for a ride somewhere in a car or the best is SUV. You should hide in the car in the last seat ( in SUV) with a rose and keep your the bag in which you have kept the ring in the seat before your seat. Tell the lover's friend to tell your lover to get something from the bag. The moment he will see the ring , you say "Will you marry me?" but stay hidden. The time he will come looking for you in the last seat you propose him.