Gwen Stefani and Blake Shelton have finally gone public as a couple, but at least one person is calling foul on their supposed story book romance.

Stefani’s ex, Gavin Rossdale, is allegedly “suspicious” over the timing of their relationship, which came hot on the heels of both Stefani and Shelton’s respective divorces, a source close to the former Bush frontman tells TMZ.

The source adds Rossdale feared the two judges on TV’s “The Voice” may have become more than friends before Stefani, 46, ended her marriage. Country star Shelton, 39, filed for divorce from his wife of four years, Miranda Lambert, 31, on July 20; Stefani split from Rossdale less than a month later.

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Rossdale, 50, believes the two kept their affair under wraps because Stefani, the former No Doubt singer, was worried he would fight her for more money in the divorce if he knew she’d cheated, the source claims.

Click here to read more in the New York Post.