Gavin Rossdale: 'Suspicious' Over Gwen/Blake Relationship

Gavin Rossdale is "suspicious" over estranged wife Gwen Stefani's story that she just became an item with Blake Shelton ... our sources say he just doesn't buy it.

Sources close to Gavin tell us he smelled something was up between Gwen and Blake before their marriage blew up. We're told he does not believe the timing of his divorce with Gwen and Blake's divorce with Miranda Lambert is coincidental.

We're told Gavin believes Gwen was painting him as a bad guy for cover ... he thinks she was worried he'd take her to the cleaners if he found out she had already hooked up with Blake.

And our sources say Gavin's gripes go beyond Blake. He can't believe she's calling him a control freak, because she demanded he NOT go on tour out of paranoia he'd cheat on her. He says she browbeat him into staying home, which greatly impeded his ability to make money. As one source said, "She just didn't let him work."

And finally, we're told he's indignant she recorded a "woe is me" song, "Used to Love You," in which she cries, "Nobody taught you how to love." We're told Gavin's scoffing at the lyrics, saying he was good enough for her for a long time.