Country music superstars Miranda Lambert and Blake Shelton are ending their 4-year marriage.

Reps for the couple told the Associated Press: "This is not the future we envisioned. And it is with heavy hearts that we move forward separately. 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."

Shelton filed for divorce in Oklahoma, according to TMZ, a move which may come as a shock to fans of the superstar singers, who began dating in 2006. They were last seen together in public on July 3 where they performed together at the Greenbrier Classic concert series in West Virginia.

The couple, who married in 2011, met while Shelton was married to his first wife, Kaynette Gern. They were paired to sing a duet of "You're the Reason God Made Oklahoma" at the CMT's 100 Greatest Duets Concert in 2005.

"I was a married guy, you know, standing up there going, 'Man, this shouldn't be happening,'" Shelton said of meeting Lambert at the duet concert on Lambert's "Behind the Music" special on VH1. "Looking back on that, I was falling in love with her right there onstage."

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Shelton and Lambert maintained that they did not start dating until "The Voice" coach ended his marriage to Gern. 

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They became engaged after Shelton proposed at their Tishomingo, Oklahoma home in 2010. Shelton told Us Weekly at the time of the engagement that his union to Lambert would be his "last marriage." They were married one year later in front of 550 guests including some of country music's biggest stars. At the time, Lambert told Us Weekly, "I'm married to my best friend! Looking forward to a lifetime of laughter and love."

The typically private couple shared a personal moment from their lives in Shelton's "God Gave Me You" music video. Lambert is seen 36 hours before their wedding telling the camera, "We made it through the unthinkable, we have made it through everything we can possibly make it through. I know we have a lot more trials and tribulations to go but I'm ready to join in with you on that journey."

The couple shared another personal moment from Shelton's life when they penned "Over You" in 2013 about losing his brother to a car accident when he was a teenager. They won Song of the Year for the emotional tune at the 48th annual ACM Awards in April 2013.

After the win, Lambert told reporters that while their careers make it difficult to spend time together, it's "moments like this together...that actually count." She continued that their marriage is more important than career highs. "Like I always say, my mom said to my dad, 'Divorce is not an option.' So, we really love each other and have a real marriage outside of all of this," adding "When this is all said and done we will be drinking a beer together on a front porch somewhere, reminiscing about the good old days, and that’s what I’m happy about."

In January, the "Little Red Wagon" singer gushed over her husband to Marie Claire

"I'm not sunshine and roses. Blake's the happiest person on the planet...He pulls me out of my darkness....literally, everything is the best about being married."

A rep for Shelton told FOX411 the couple would not be releasing any further statements. A rep for Lambert did not return FOX411's request for comment. 

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