The couple, who met through a private Bachelor Facebook page last year, reportedly announced the news at the fourth reunion of the show's stars in Colorado.
"I have to have a guy with a sense of humour and John has that sense of humour. I don't like to be away from him. Before, I loved long distance because it gave me my own space, so I think everything was just different with him," said Durr.
The pair are apparently planning to wed in front of 500 guests, including past show contestants, in November.
Durr appeared on Lorenzo Borghese's season of The Bachelor, while Presser was seen in the Jillian Harris-fronted season of Bachelorette last year.