It could also be a big incentive for single people to find someone to share their adventures. I imagine if I were single I would not be looking forward to lonely evenings in a foreign country. They have had more than one seminar at FSI about "Singles in the Foreign Service." There was talk that when you do get overseas, you may need to be careful that some foreigners are seeking an American spouse not for their many fine qualities, but for a green card.
I have heard it can also be a wake-up call for some married folks. Some officers learn their spouses aren't really world-wide available and are not happy to hear that most new officers don't go to Europe.
For us, the whole process of thinking about moving overseas, packing up all of our material possessions, and saying goodbye to our friends and family involved a lot of thinking about our lives and what made us happy together. I was just reading the other day that sharing adventures together is one of the best things a couple can do. Talking to some of the more experienced FS folks was very encouraging along these lines, and that FS life brings spouses and children closer by necessity. You have to rely on each other more, you spend more time together, and your family is the one constant in your life even though you are changing posts frequently.
One other couple now in training told me they planned to renew their wedding vows in every country. How romantic!