An insider has said that Middleton, 37, wants "rural rival" Hanbury, 35, "phased out" from her inner circle.
The Sun has reported that royal sources say that their once close friendship is "in tatters."
Prince William has allegedly tried to mediate between the two women, as he and Middleton have gone on several double dates with Hanbury and her husband David Rocksavage, the Marquess of Cholmondeley.
But Middleton reportedly doesn't want anything more to do with Hanbury.
"It is well known that Kate and Rose have had a terrible falling out. They used to be close but that is not the case anymore," a source told The Sun.
William would like Middleton to mend fences with the prominent couple, "But Kate has been clear that she doesn't want to see them anymore and wants William to phase them out, despite their social status."
Hanbury and her husband, who have twin boys, live just three and a half miles away from Anmer Hall, the country home given to the Duke and Duchess by the Queen.
Now Middleton and Prince Williams' three kids won't have their playmates!
As Radar has reported, there has been much hubbub about Middleton supposedly feuding with Prince Harry's wife Markle, 37.
Royal insiders have said both Middleton and Prince William believe Markle's values are very different from their own, and they don't appreciate how she treats the palace staff.
The Prince brothers have planned to "split their staff in an effort to ease tension" between their wives, The Mail On Sunday sources recently claimed.
Now Middleton appears to be cutting Hanbury and Rocksavage, who were front and center as wedding guests when she and William tied the knot eight years ago.
Kensington Palace has declined to comment.