Kelsea Ballerini Hints at Falling Out with Halsey, Marriage Issues on New Song 'Doin My Best'

For Kelsea Ballerini, life is subject to change — and that includes her relationships.

The country star, 29, released her new album Subject to Change on Friday, and appeared to reference her friendship with Halsey and its apparent end in the lyrics of the song "Doin' My Best."

"I was friends with a pop star/I put 'em on track four but/Wish I could take it back, I would've never asked/If I knew we wouldn't talk anymore," Ballerini sings on the track.

The line seems to be a thinly veiled reference to Halsey, 27, who collaborated with Ballerini on "The Other Girl," the fourth track on the country star's third album Kelsea.

When asked about the line, Ballerini told Consequence that there are a few songs on Subject to Change that she's "a little nervous for people to hear."

"I'm a human, and life is messy, and there's some things that I wanted to take ownership for," she said. "It's a little embarrassing and a little cringey, but that's my human experience."

The "Heartfirst" singer previously discussed her friendship with Halsey with PEOPLE in 2018, and said that they first met in Nashville after Halsey came to town on the Hopeless Fountain Kingdom tour.

"I had met her before, but we'd never really hung out," Ballerini said at the time. "I'm obviously a really big fan of her music, so I went to the show with my friends and afterwards said hi, and she didn't have a show the next day, so she was like, 'Let's go hang!' And I was like, 'Yep!'"

One thing led to another, and the singers hit the town for a night of beers and karaoke — all of which they documented on social media.

"We just hung out a few places in Nashville," Ballerini said of their night out. "We're both really similar in age and had a lot to talk about; it was cool to be around someone who's so creative and so driven and so down-to-earth. She really is so lovely. I feel like I made a new friend."

Ballerini told Taste of Country in 2020 that she wrote "The Other Girl" about a month after their meeting, and knew she wanted to feature Halsey on the track.

"I've never had collaborations on my records before, and it wasn't for lack of trying," she said. "On [Kelsea] I was like, 'I only want collaborations if they're my friends. I don't want to go to some pop star that I don't know… I just want to do it if it makes sense to me."

Halsey also spoke about the collab in a 2020 Instagram Live with Ballerini, and said that in order to channel the pain of the lyrics, she and the country star had to look to the past.

RELATED VIDEO: Kelsea Ballerini on Why She's Being Honest with Her Fans During New Period of 'Change'

"It was really cool, because [Ballerini] and I were both in really good places in our lives and drawing from old hurt," Halsey said, according to The Boot. "To be clear, this [song] is a fictional event. But just us representing those two sides of women in the equation, being like, "No, we're not gonna let misogyny turn us against each other, instead we're empowered."

Subject to Change is a deeply personal record for Ballerini, and the rest of the lyrics of "Doin' My Best" find the star reflecting on the last two years in detail. She begins the track by saying that 2020 "was a weird year," and her album, Kelsea, "dropped at a weird time," as it came out that March.

She also sings about how she went to therapy and was eventually joined by then-husband Morgan Evans, because, as she notes, "when you get married that young, you got a lotta s— you gotta get through."

Ballerini was 24 when she and Evans tied the knot in December 2017. Though she talked frequently about how the pair sought couples' therapy, she filed for divorce from the musician last month.

"This deeply difficult decision is the result of a journey of love, growth, and effort that ultimately has come to an end," she said in a statement at the time. "It's hard to find the words here...but I feel extremely grateful for the years of marriage to Morgan and hopeful for the next seasons."

Ahead of the release of Subject to Change, Ballerini opened up to PEOPLE about the "beauty" and "messiness" in her soul searching that inspired the record.

"It's really my post-pandemic project. Like everyone else in the world, I was forced to sit in stillness and I'm not good at that," the singer, 29, tells PEOPLE. "I like to be in full sprint all the time, working and playing shows and making records. And that wasn't an option. In that time I kind of woke up and I was like, 'Oh, I'm not 19 anymore. That's weird.' And I have a lot of life to process and a lot of time to do it."

She continues, "I think in that unraveling of all these beautiful, amazing experiences that I had gotten to have over the years in my career and my personal life ... it really unlocked this honesty and more so than the honesty, the guts to go there in some ways. And I think that's heard throughout the whole project."