Blake Shelton & Miranda Lambert 'cheating' RUMORS: 'The Voice' star gets 'too flirty' with sexy supermodel Alena Shishkova on Twitter, wife jealous?

Blake Shelton and Miranda Lambert make an adorable country music couple - so what's with all of the cheating rumors!?

The National Enquirer reports that Shelton's relationship with Lambert is struggling yet again. Apparently, "The Voice" judge was caught getting "a little too close" with stunning Russian model Alena Shishkova. And Lambert was NOT happy about it.

So where did this supposed "flirting" begin? On Twitter, of course.

Shirshkova started following Shelton on the popular social networking site, so the "Boys 'Round Here" crooner re-posted a positive shout-out about it:

@blakeshelton: "'@MlSSALENA92: @blakeshelton did you know you got followed by supermodel @alenashishkova on Valentines Day?' Yee haw!!"

Shishkova is gorgeous, but that doesn't mean Shelton plans on leaving his wife because the supermodel acknowledged him on Twitter!

Still, an alleged insider reveals, "Miranda went nuclear on Blake when she caught him drooling over Alena... She accused him of purposefully embarrassing her with highly inappropriate behavior." 

Apparently Lambert ordered Shelton to stop following Shishkova on Twitter, but he refused.

"The feud over Alena has set off World War III between them," the source explains.

Oh, my.

Do these "marriage in crumbles" rumors sound familiar?

Old news - and still untrue.

Another "legit" source close to the situation tells Gossip Cop that the latest report is "just more of the same nonsense." 

Surly Shelton and Lambert agree.