Bitter Gavin Bugs Blake Shelton

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Bitter Gavin Rossdale likes to yank Blake Shelton’s chain every chance he gets, and now The National ENQUIRER can reveal the rocker is REALLY ticking off his ex-wife’s new hubby by offering him fashion and diet tips!

Bush music man Gavin, 56 — who split from 52-year-old Gwen Stefani in 2015 after 13 years of marriage and three kids — is frothing with jealousy over her new husband, 45-year-old Blake, sources snitch.

“Gavin’s the real troublemaker here,” spills a spy. “He teases Blake to no end, referring to Gwen as ‘my beautiful ex-wife.’ He has this way of getting under Blake’s skin. “Lately, Gavin’s offered to be Blake’s fashion and diet guru because the guy’s put on a few pounds and can’t seem to wear anything besides dad jeans and boring shirts.

“Bottom line, he feels Blake’s not good enough for Gwen and wants to stick it to him any way he can!”

Voice coach Blake, who married Gwen last summer after six years of dating, has a tough time fighting back, spills an insider.

“Blake is very alpha-male so he’d never show it bothers him, but it absolutely does,” tattles the tipster. “Just the mention of Gavin’s name sends a dark look across his face.”

As The ENQUIRER previously reported, sources say Blake would love to adopt Gwen’s boys, Kingston, 15, Zuma, 13, and Apollo, 7 — and Gavin has blocked him every step of the way.

Tattles the spy, “That’s a big part of why Gavin goads him. He wants to be sure Blake knows his place!”