Cameron Platt, who just finished her master’s degree in English and United States history, took to Facebook to gush about her 71-year-old fiancé, writing that their engagement "will come as a surprise to many” after just six months of dating.
She wrote she met Lee Mitchell while she attended Princeton University - one of America's top colleges - where he was head of the English Department.
Platt, who lists Oxford as her home, said she took one of his classes five years ago when she was 20-year-old.
She shared a photo showing her and Mitchell beaming over wine at a restaurant, and another image of a diamond-crusted engagement ring.
She wrote on Facebook: “I was taking his lecture course on Henry James and William Faulkner.
"Lee was little more than a stranger to me then, but he captivated me with his brilliance, sensitivity, and passion.
“His lectures changed forever the way that I think.”