As others have said, you will get the gold benefits as long as your name and MR # appear on the reservation. You may or may not get the points and nights stay credit, since your fiancee has to pay for the work conference. According to MR T&CS (bold added):

A Member is eligible to receive Points/Miles for a qualifying stay at participating Marriott brand hotels or Ritz-Carlton hotels for his/her room and up to two additional rooms. At least one of the rooms must be reserved and registered in the Member's name and the Member must pay for all rooms, which payment arrangement must be requested at time of hotel check-in. The Member must also stay in one of the rooms.

If you do receive the nights and the points look at it as a gift from MR. I have personally had it happen both ways when my spouse paid for a conference.


Regards,

RIP...