The tenth-season American Idol finalist and the Twilight saga star have gotten engaged just seven weeks after McDonald confirmed to Reality TV World they were dating, Peoplereported Monday.
"I love him and I don't care," Reed told People last month.
"I've never met anyone like him. I've never met anyone who has such a good solid heart and comes from such a good solid family and is just a genuine person. We have the exact same sense of humor. I've never laughed so much with anyone as I do with him."
Speculation that the couple had gotten engaged surfaced on Sunday when the Twilight, New Moon and Eclipse star flashed a diamond on her left hand's ring finger while walking the red carpet with McDonald at the MTV Movie Awards on Sunday night.
"He's the one. He's the one," the 23-year-old told E! News when asked if she and her 26-year-old boyfriend were ready to tie the knot.
Reed told E! News that McDonald -- who made it to American Idol's Top 8 but then became the first male finalist eliminated from the show's tenth season -- has been writing and dedicating songs to his new fiance.
"He says he's going to release a Nikki Reed EP," she said.
The actress, who recently wrapped up filming the Twilight saga's fourth installment Breaking Dawn, later joined the rest of The Twilight Saga: Eclipse's cast onstage at the MTV Movie Awards to accept the Best Movie award.
McDonald met Reed when American Idol's finalists attended the premiere of Reed's The Little Red Riding Hood movie in March. A March American Idol broadcast showed Reed approaching McDonald and gushing that she felt he was "amazing" and "was blushing."
McDonald subsequently told Reality TV World on April 15 he was in a relationship with the actress.
"Yes. Me and Nikki Reed are dating. It's officially true," McDonald said, putting the rumors to rest.
"She's super cool. She's super smart and a really cool girl. I'm happy with it. We've been hanging out here and there and we're both pretty busy. But it's been fun so far."