Country stars Miranda Lambert and Blake Shelton may be headed for divorce, according to InTouch Weekly via RadarOnline.

An InTouch source claims that Lambert and Shelton are "barely together" and Lambert fears that the constant time apart will cause them to "continue to grow apart."

Neither Shelton nor Lambert have confirmed the divorce rumors. However, RadarOnline reports Lambert recently admitted that she and Shelton's tour busses "literally pass in the night, heading in opposite directions on the same highway."

Both Shelton and Lambert are currently on tour and the literal and emotional distance between them has allegedly taken its toll on their relationship, explains ShowBiz Spy.

"They can go days without speaking. They'll send a couple of texts, but that's all they have time for. It's taking a toll on the marriage," a ShowBiz Spy source claims.

Another cause for the couple's rumored estranged marriage is the difference in lifestyles. Lambert -- who has adopted a healthier lifestyle and lost 45 pounds -- allegedly wants Shelton to follow suit and stop drinking and partying. 

"She wants Blake to stop partying so hard and get healthy like she did. But he has no plans to slow down," the InTouch source adds. 

Shelton's constant partying has also led him to develop a wandering eye. Because of his rumored infidelity, Lambert has developed "trust issues" and questions her husband's commitment to her, ShowBiz Spy reports. 

Last year, Shelton was rumored to have had an affair with then-25-year-old singer Cady Groves.  And according to RadarOnline, Shelton first met Lambert and dated her while he was still married to high school sweetheart Kaynette Williams. 

Now that Lambert lives a cleaner lifestyle, she also wishes to spend less time in Hollywood, where Shelton tapes "The Voice," and more time in Oklahoma, explains RadarOnline. 

Yet, neither of them can come to a compromise on where to stay. 

Still, Lambert is dedicated to making her marriage work and has no plans for divorce despite the couple's many rumored marital issues, RadarOnline reports.