Charlotte will be the second of the five children in her family to marry (she is the youngest). Her oldest sister Lady Frances is married to Rostislav Gabinsky and has a son Alexander who will be 2 this year.
Jaime is the eldest of seven children. He will be the first in his family to marry. His siblings are all significantly younger then him, the closest in age being 10 years younger then him (range from 5-17 while Jaime is 27).
According to the company website for Jaime's company, he is manager of their real estate and construction department in Paris. As his fiancé works for citi bank in London I wonder who plans on a move (I assume once married they don't plan to live in different countries).
Once again we see another example while marrying royals/aristocrats has become almost extinct in the reigning houses, the non-reigning houses still marry at least among the aristocracy often enough. But they tend to socialize in those circles so its more likely.