The 19-year-old model discussed her status with the 21-year-old singer at the amfAR New York Gala on Tuesday, telling E! News she and Bieber are close but not exclusively dating.
"We are not an exclusive couple," the star said. "He's about to go on tour. Relationships at this age are already complicated, but I don't really like to talk about it because it's between me and him."
"I live a very public life and I have to keep things personal or else I have no personal life," she explained. "It really is my personal business. And I like to think my relationships are not between me, the person and the whole entire world. It's hard."
Baldwin spoke out after months of dating rumors and Bieber's declaration of love in the March issue of GQ. The magazine previewed the singer's cover story Tuesday, quoting him as saying, "[Hailey is] someone I really love. We spend a lot of time together."
"He's really funny. We have a good time together," Baldwin told Entertainment Tonight in response. "He's just really sweet. He's a good kid, he has a good heart and I love him."
Baldwin and Bieber are longtime friends who were first romantically linked in 2014. The model said she and the singer are "just friends" in February 2015, but Bieber shared a photo of himself kissing Baldwin in St. Barts last month.
Baldwin is daughter to actor Stephen Baldwin and his wife Kennya, and sister to 12-year-old Alaia. She has modeled for Ralph Lauren, Tommy Hilfiger and Topshop, while Bieber last released Purpose in November. The album debuted at No. 1 on the Billboard 200.