D'Agostino, 50, and Rothschild, 52, were caught in the Hamptons together over the Labor Day weekend, while de Lesseps, 52, was alone in Sag Harbor.
"Anna has been friends with Tom for 12 years," an insider told Radar. "She hates Luann!"
Rothschild isn't the only girl D'Agostino has been wooing since he filed for divorce from de Lesseps in August. Radar caught him cozying up to a woman at a local New York bar just hours after splitting from his reality star wife, and again with another blonde just weeks later.
Stay with Radar for more.
We pay for juicy info! Do you have a story for RadarOnline.com? Email us at firstname.lastname@example.org, or call us at (866) ON-RADAR (667-2327) any time, day or night.