"It's with great sadness that Tom & I agreed to divorce," she wrote. "We care for each other very much, hope you respect our privacy during this sad time!"
The couple got engaged in February 2016 and married on New Year's Eve. The relationship was chronicled on the Bravo reality show and saw many of de Lesseps' co-stars question her relationship amid rumors of D'Agostino's infidelity.
Just weeks ago, de Lesseps and D'Agostino got into a public argument at a restaurant, E! News reported.
"They have had their share of rough moments. There was an argument in a restaurant last week, they're not denying that," a source said. "Marriage is tough and they're working on it."