"Life & Style" magazine keeps trying to start rumors that BLAKE SHELTON has been getting a little "too friendly" with a singer named Cady Groves . . . and that MIRANDA LAMBERT confronted her.



Blake laughed it off Sunday by Tweeting, "Hey @MirandaLambert . . . I just read in a tabloid that our marriage is falling apart!  [Eff]!"  Miranda quickly responded, "Oh no!  Can't wait to read if we make it or not." 



the funny thing about this story is that Blake and Miranda were laying right next to each other when they were tweeting back and forth.

Blake was in Cady's video called "This  Little Girl"