It could work
*object of affection opens box, inside, where a ring should be, is some cash. Video starts*
"Agent <name of lady here>, A man of your acquaintance, Mr <your name here> has contracted a serious illness called "Love". We are, as yet, unsure if this is the work of the sinister agents known as C.U.P.I.D. It is possible this condition may cause his state to deteriorate and it appears you are the only one who is able to bring him happiness and stability. It is possible this assignment may last as long as he remains alive. Your mission, should you choose to accept it, is to marry <your name here>. If you accept this mission, you should use the currency located in this box to travel directly to Terminal 2, European flights and proceed directly to the lounge area where your contact will be waiting."
Wait for her somewhere conspicuous, smile, act casual and present her with the real ring box closely followed by the tickets to Paris. Job Done. Claim your "I'm a romantic bastard, me" prize.