She's not buying it!

Blake Shelton, 39, and Gwen Stefani, 46, confirmed dating rumors right before the CMAs earlier this week, but the country crooner's ex-wife Miranda Lambert allegedly knew something was up way before then.

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“Miranda believes something’s been going on between these two for a lot longer than they’re letting on,” a source told Hollywood Life. “She doesn’t buy their story that it’s totally brand new."

As Life & Style previously reported, the 31-year-old singer was shocked that her ex-husband moved on so quickly after four years of marriage. She could barely keep it together during her acceptance speech for Female Vocalist of the Year.

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“She won one of the best awards of the night and she couldn’t even enjoy it. She was just holding back tears the whole time,” the source added.

Despite all the drama, the "Automatic" singer is sticking to her story. "Miranda’s sure the truth will come out eventually, it always does.”