Grammer met the British stewardess on a flight to London in 2010, while he was still married to his wife Camille, and the two immediately hit it off.
But Walsh admits she had huge reservations about becoming the "other woman", even thought Grammer insisted his marriage was over.
During an interview with Oprah Winfrey for U.S. TV series Oprah's Next Chapter, which aired in America on Sunday (26Aug12), she said, "I'm not proud of the way we started out... I felt terrible,... but I fell in love."
And Walsh reveals she only agreed to go on a date with Grammer, who played the title role of Frasier Crane on hit TV sitcom Frasier, after a series of strange occurrences.
She adds, "I wouldn't have (tried to date him, knowing he was married), it's against my morals. Anyway... I got the coach (bus) to London and I sat there and I hadn't heard from him. And I thought, 'Shall I call him? Shall I call him?' And I thought, 'No, I can't, I can't. If I should call him, I want a sign,' and I put my head down and I looked up and we drove past a restaurant or a shop and it was called Frasiers.
"And I thought, 'No, no,' and I said, 'I want another sign, I need another sign.' I looked up again and we drove past Crane Jewellers. And then I said, 'I want one more sign, if I'm supposed to call him, I just want one more,' and as I thought that we drove past the hotel he was staying in."
Grammer left his wife for Walsh and weeks after finalising their divorce, he walked down the aisle with his new bride, who is 25 years his junior. The couple welcomed a baby daughter, called Faith, last month (Jul12).