The love of money... She was attracted to him because of his money and banking business.
I saw exactly that in college. The foreign students, including the ones from South America and Central America, wined and dined the American college girls. They had fabulous adult type cocktail parties, for which they bought the girls expensive gowns and jewels. The American girls were totally bedazzled and all of them said they were treated like princesses.
Then came the boys’ graduations. Everyone of them broke up with their American girlfriends, told them they had been engaged since childhood to girls from back home and went so far as to tell the American girls that they had just spent 3-4 years being mistresses. Other names were added to that.
Lots of tears and misery in the dorms every June.