Princeton University’s 2016 valedictorian hit the books — then hit on her 71-year-old former professor, to whom she is now engaged.

Cameron Platt, 25, who was a star student at the Ivy League university and just finished her master’s degree at the University of Oxford, recently gushed on Facebook in a private post about her septuagenarian fiancé, Lee Clark Mitchell, who will be 72 in June.

Platt wrote that she met Mitchell, who has served as chair of Princeton’s English Department, when she took one of his classes during her sophomore year five years ago, in the fall of 2013.

“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,” Platt wrote in the April 18 post. “His lectures changed forever the way that I think.”

By the time Platt was graduating at the top of her class with a degree in English and a certificate in theater, Mitchell had become a “devoted mentor” to her, she said. But after graduating, she left for the University of Oxford to pursue a master’s degree in English and United States history as a Rhodes scholar.

During her two years in England, loving thoughts of her gray-haired prof frequently came to mind, she said, even with an ocean between them and her undergraduate studies long in the rear-view mirror.

“I was surprised to find how much I still thought of Lee — and soon I understood that I felt something for him that I’d not fully acknowledged before,” Platt wrote in the Facebook post.

“At the end of my two years in Oxford, after much reflection, and with encouragement from my wonderful friends, I resolved to shoot my shot.”

The young scholar reached out to Mitchell this past September and asked him out for a date at the Metropolitan Museum in Manhattan, where they frolicked through the galleries like “shy teens, eager but tentative,” Platt wrote.

She said Mitchell, likely confused by his young suitor’s attraction to him, spent most of the first date trying to figure out if it was actually a date, while they were both “unsure of how to test new boundaries with each other.

“At last, to our amazement, we broke through. Something then sprouted from a seed that neither of us had known that we’d planted, and we realized that the force of feeling that we’d long had for each other and called by other names (admiration, wonder, devotion, gratitude) held within it the hope and the potential for love,” Platt went on.

Platt, who is 46 years younger than her fiancé, wrote in the post that she kept their relationship “private” for the past half year, but once they became engaged after about seven months of dates, she was ready to make the relationship public in a post that’s since garnered nearly 300 likes.

She acknowledged that the announcement “will come as a surprise to many” and that the couple had concerns about their relationship, given their “different stages of life.” But she said that more importantly, she’s deeply in love with Mitchell.