In 2005, a married Blake Shelton and an engaged Miranda Lambert sang a duet together on CMT’s 100 Greatest Duets event. Viewers could see sparks fly between the two country singers, and the feeling was even stronger for the two of them. Shelton said he immediately began to fall for her, which sent him into a panic.

Blake Shelton knew he shouldn’t be developing feelings for Miranda Lambert

Shelton and Lambert met in 2005 and hit it off immediately.

“He’s hilarious,” Lambert said, per Entertainment Weekly. “We had instant chemistry, just like messing with each other, and he’s real easy to be around.”

Their connection was almost too strong, though. Shelton realized he had feelings for Lambert as they sang “You’re the Reason God Made Oklahoma” at the CMT event. At the time, he was married to Kaynette Williams, and Lambert was engaged to Jeff Allen McManus.

“I’ve never had that kind of experience with anybody,” he said. “I was a married guy, you know? Standing up there and singing with somebody and going, ‘Man, this shouldn’t be happening.’ Looking back on that, I was falling in love with her, right there on stage.”

Lambert felt similarly, but felt she should stay away from him, noting that she “knew he was married.”

“I knew better, like, this is off-limits … I didn’t know what to do with it, it was, like, my first duet with some other country star, and I didn’t know if it was just initial butterflies because of that,” she said, adding, “I don’t know what it was. It was just this draw to each other.”

Blake Shelton and Miranda Lambert announced their divorce in 2015

Ultimately, Shelton and Lambert’s chemistry won out. They began dating and married in 2011. Just four years later, though, they announced that they had finalized their divorce.

“This is not the future we envisioned. And it is with heavy hearts that we move forward separately,” they said in a statement, per ABC News. “We are real people, with real lives, with real families, friends and colleagues. Therefore, we kindly ask for privacy and compassion concerning this very personal matter.”

The couple reportedly are not on good terms

In the years since their divorce, Shelton and Lambert have both moved on with different partners. They reportedly hold on to animosity, though.

“Miranda doesn’t want to attend any event where Blake is the star attraction, and vice versa,” a source told Life & Style. “Their egos can’t handle it, and the brutal reality is that they can’t stand the sight of each other. They’re totally competitive, and there’s no love lost, and they don’t want any awkward confrontations. Some might say they don’t want the other to steal their spotlight.”

The source said that neither singer appears prepared to let go of their grudge.

“Their friends roll their eyes and think Miranda and Blake should get over it and act like grown-ups, but they’re stubbornly holding onto grudges,” the source said. “They might forgive, but they’ll never forget.”