The 47-year-old singer shared a point of contention with the 40-year-old country star while discussing their recent trip to Disneyland on Wednesday's episode of The Tonight Show starring Jimmy Fallon.
"I took him to Disneyland. He'd never been to Disneyland. I was like, 'Your life is not even complete yet! Like, what are you doing?'" Stefani told Fallon.
"I was nervous because for me, I just go anywhere. I know I'm going to get hounded or pictures [taken] or whatever, but I don't mind. For him, he's not used to that," she said. "We went. It was crazy. There was like a billion people there."
"He won't do the rollercoasters. That was almost a deal breaker for me," the star joked. "He doesn't fit in anything. We did go on the Matterhorn [Bobsleds]. He did that one. But he barely fit inside the little [car]. His knees were up."
Stefani had described Shelton earlier in the episode as a "country boy" who "does not like going out." She said her beau spends "most of [his] time" in "the woods" and feels more comfortable in the country than Los Angeles.
"I think he's quite miserable when he's not in the woods or, like, somewhere in camo. He really likes to be camouflaged," the star shared.
Stefani and Shelton confirmed their relationship in November 2015 following their splits from their respective spouses, Gavin Rossdale and Miranda Lambert. The couple will both serve as judges on The Voice Season 12.
"It's just so fun. It's so easy and comfortable," the singer said Wednesday on the Today show of working with Shelton.