"The whole thing has been crazy," Stefani said of falling in love with Shelton following her 2015 divorce from husband Gavin Rossdale. "I mean completely, totally crazy."
"For a long time, I could not understand why I'd had so much heartache in my life," she added. "I have parents who are still married and in love. I had such loving role models. I didn't understand it."
Stefani, who was previously brokenhearted after her split from Tony Kanal, broke up with Rossdale in 2015 after nearly 13 years of marriage. She poured the pain of her divorce into her third studio album, This is What It Feels Like.
"What I learned was that my heartbreak was supposed to happen, that it was my purpose to write about and share my story," the singer said. "I met at least 50 to 100 people before each show on my tour and got to hear that my truth and my story translated, and I feel very lucky and honored knowing that."
Stefani and Shelton confirmed their relationship in November 2015 following their divorces from Rossdale and Miranda Lambert, respectively. Stefani couldn't help but gush about Shelton after he was named People's Sexiest Man Alive of 2017 last week.
"He's perfect for it," the star told the magazine. "Somebody that is funny and has a sense of humor is sexy -- that's the No. 1 thing."
"[He's] somebody that is at the top of their game and talented and genuine and cool and generous and just not self-aware at all -- completely a man," she added. "He doesn't even know how cute he is."