The two were first rumored to be wed after Hudson's mother, Oscar winner Goldie Hawn, 66, was misquoted in the U.K.'s Evening Standard's ES magazine. "When my daughter Kate married an English rock star it didn't worry me," Hawn was quoted as saying. "All that matters is that the relationship is a good one."
Hawn set the record straight on Twitter Monday, writing: "Darling, once again twisted the truth. They aren't married. . . They never get it right."
Indeed, an insider previously told Us Weekly that Hawn -- who has never wed longtime love Kurt Russell, 61 -- frequently refers to her Overboard costar as her "husband." It appears Hawn did the same when talking about her daughter's fiance.
Something Borrowed's Hudson, 32, has been engaged to Muse frontman Bellamy, 33, for nearly a year. They welcomed son Bingham on July 9, 2011. Hudson's new movie, A Little Bit of Heaven, is in theaters May 4.