Or they can visit the real Golden Triangle, Laos, Cambodia and Thailand.
One has to be careful about theft in Laos and Cambodia, but I didn’t feel threatened physically as I did in India.
Wherever your daughter and her BF goes, tell them not to venture outside the tourist spots. These are not the countries to explore on your own safely.
For Thailand, all the touristy spots are quite safe, again one has to use common sense everywhere, in San Francisco, New York, Paris or Chiangmai. My D was robbed in the daylight in Trafalgar Square because she took a shortcut while jogging back to her LSE dorm.