Miranda Lambert -- 'The Voice' Helped Ruin Our Marriage

Miranda Lambert claims cheating was not the only reason her marriage fell apart ... Blake Shelton was way more into "The Voice" than her, and she felt like an abandoned wife ... so say our Miranda sources.

Our sources say Blake's hit TV show was a constant source of conflict between them. She says he had to spend between 7 and 8 months a year in Los Angeles ... a place she "hates." Nevertheless, the sources say she would fly to L.A. to see him -- sometimes just for a day.

But Miranda claims he rarely reciprocated by coming to Oklahoma or wherever she was working.

The sources say Miranda felt abandoned and ultimately said, "This is no way to live."

As for the cheating ... both sides are not backing down and accusing the other of infidelity.