Story highlights Moore's costars confirmed the engagement

She posted about their dating anniversary

(CNN) The "This Is Us" cast is such a family, and just like your relatives they apparently can't keep a secret.

One of the stars of that show, Mandy Moore, is reportedly engaged to her boyfriend of two years, indie rock band Dawes frontman Taylor Goldsmith.

"I was just in the studio with [Moore's] boyfriend, well now fiancé, Taylor," said Sullivan, who plays Toby on the show. "He didn't say a word. He seemed a little effervescent, but he's always pretty effervescent."

Sullivan said he had yet to get all the "How did he pop the question" details from Moore, but said he had seen her engagement ring.

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