In Goblet of Fire, Mrs Weasley is seemingly upset with Hermione, and it appears to be due to reading what Rita Skeeter wrote about her in the newspaper.
Mrs. Weasley knew Hermione pretty well at the time, so why would she trust a journalist over her personal impressions?
Quotes for context:
In the chapter "The Madness of Mr. Crouch"
Percy's letter was enclosed in a package of Easter eggs that Mrs. Weasley had sent. Both Harry's and Ron's were the size of dragon eggs and full of homemade toffee. Hermione's, however, was smaller than a chicken egg. Her face fell when she saw it.
"Your mum doesn't read Witch Weekly, by any chance, does she, Ron?" she asked quietly.
"Yeah," said Ron, whose mouth was full of toffee. "Gets it for the recipes"
also in the chapter "The Third Task"
Harry looked between them, then said, "Mrs. Weasley, you didn't believe that rubbish Rita Skeeter wrote in Witch Weekly, did you? Because Hermione's not my girlfriend."
"Oh!" said Mrs. Weasley. "No -- of course I didn't!" But she became considerably warmer toward Hermione after that.