His wife, Danielle Crittendon, did something (can't recall what) which took the lustre off Frum's star at the WH, after which he left voluntarily. He wasn't fired, and the "forced to leave" argument is debatable.
Thank you. :)
Now you're refreshing my memory--I think she spoke to the press, or someone, and it got out, about details about which parts of Bush's speech could be attributed to him--such as the phrase, "the Axis of Evil."