"I think the world of him, and he's an amazing person," she said. "That's kind of all there is to it."
Her comments are especially meaningful given that Ariana's grandfather passed away from cancer this July at 90 years old.
"He was like, 'You're a star, I know in my heart you're going to make this family so proud. You're a blessing,'" she told Seventeen magazine about her grandfather's sweet words to her before he passed away. "And I was like, 'oh my God,' and started crying, and I trusted it."
Previously, Ariana had only responded that she was "happy" when asked about the relationship between her and Big Sean.
"Y'all are putting me on the spot!" she told Matt Lauer during her Today show appearance in late August, adding, "I'm happy."
And just like that, music's worst-kept secret is officially out in the open!
Though for Big Sean's sake, let's just hope Ariana doesn't kiss and tell. In August, she made headlines when she revealed that her new song "Break Your Heart Right Back" was about her getting cheating on by an ex-boyfriend with another guy.
ET talked to Ariana about the controversial comments in the video below.