Rosie O'Donnell: 'My Gaydar Was Way Off' with Michelle Rounds

By Tim Nudd

10/10/2011 at 08:20 AM EDT

Rosie O'Donnell was attracted to Michelle Rounds the moment she saw her in a Starbucks this summer. But she never thought it would be reciprocated.

"I thought she was a 28-year-old heterosexual girl, because that's what she looked like to me. And she's a 40-year-old gay woman," O'Donnell, 49, tells ABC's Nightline in an interview airing Monday night.

She adds with a laugh: "My gaydar was way off!"

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But O'Donnell, who recently said she's in love, thinks maybe it's a good thing she thought Rounds was straight. "I think if I had known that she was gay, I wouldn't have been brave enough to talk to her," she says.

O'Donnell's new nightly talk show, The Rosie Show, debuts Monday on the OWN network.