The actress admits she had never watched Idol before the season that featured MCDonald and it was a huge coincidence that they met on the red carpet at Twilight filmmaker Catherine Hardwicke's movie Red Riding Hood.
She explains, "Taylor (Lautner)... is really into American Idol, so we would have Idol dates while we were filming.
"I never go to premieres of films I'm not in but I've known Catherine Hardwicke since I was five years old and she called me and asked if I'd go to the one in Vancouver. I actually wasn't in Vancouver.
"I was driving home from the airport in L.A. and she said, 'Can you stop by the premiere?' My hair was dirty, I was a mess, I called my dad and I said, 'I'll pick you up, we're going on a date'... It was 4pm, I had to find a dress, I was tired, hadn't washed my hair and had to be there at six."
At the premiere she spotted her Idol idol and her dad Seth helped her pluck up the courage to speak to him: "My dad said, 'You should go and say hi.' Mind you I hadn't been on a date in, like, a year and a half."
And the magic moment was captured for eternity on camera.
Reed tells U.S. news show Access Hollywood Live, "You can YouTube that moment... It's so horrible... It's the worst thing... It's something like me going, 'Oh, wow, hi, you're awesome and I should go hide under a rock now'."
She tells Zooey magazine, "I walked over to Paul and knew I was in love within one second of saying hi. It was the craziest thing that has ever happened to me in my life."
The couple wed seven months later, in October, 2011