"It's awesome," Maddie, 20, toldEntertainment Tonight during rehearsals for the American Idol Live! 2018 Tour. "I mean, it's like we get each other. We're already reading each other's minds, knowing what we're gonna do next."
Caleb, 19, elaborated, "it's like dueting with yourself, almost" when the couple sing together.
As previously announced, the Idol tour kicks off July 11 in Redding, CA, and the show's last stop will be in Washington, D.C. on September 16.
Caleb and Maddie began dating on January 21 but kept their romance a secret until the live season finale aired in May, when Caleb announced Maddie is his girlfriend right before the pair performed a romantic duet of "Over the Rainbow."
"It was one of those things where I didn't want it to affect anything, and I didn't want to exploit my feelings for her because they're very, very real. Once voting was over, I was like, 'Shoot, I want the world to know,'" Caleb explained to ET at the time.
"We were just playing it by ear, but we really wished that this could happen," Maddie added, "and just that it happened, I'm just so happy and so on top of the world. I can't even believe this is my life, so it's pretty amazing."
While singing "Over the Rainbow" together, Caleb initiated some sweet gestures, such as hand holding, as Maddie just blushed and appeared giddy onstage the entire time.
At the end of the finale, the couple were surprised with a free trip to Disney's Aulani resort in Hawaii.
Caleb and Maddie weren't the only contestants on ABC's revival of American Idol to enter a relationship this season. Third-place finisher Gabby also began dating Top 5 contestant Cade behind the scenes.