The Lancaster County Historical Archives references another book Professor Klein wrote on James Buchanan and Ann Coleman. The short story is that James Buchanan, an attorney, fell in love with Robert Coleman’s youngest daughter, Ann Caroline Coleman. Mr. Coleman, who had risen from penniless immigrant to wealthy ironmaster, felt Buchanan was beneath him, and so refused to let Ann see him again.
Ann then died under mysterious circumstances, leading many to conclude that she committed suicide (which was taboo at the time). Mr. Buchanan, meanwhile, never married, and went on to become America’s only bachelor President. I also found another article that said James Buchanan ordered his letters burned upon his death, but the surviving letters were reprinted in a book called “President James Buchanan” by — you guessed it — Professor Philip Shriver Klein.