Now Gavin Rossdale reckons Gwen Stefani's the cheater.

She kind of always knew she’d end up becoming his ex-girlfriend.

Now that Gwen Stefani has officially moved on with Blake Shelton, it’s time for the lascivious rumours of infidelity to begin.

TMZ is reporting that Gavin Rossdale, 50, is “suspicious” about Stefani, 46, and 39-year-old Shelton’s story that they have “very recently” started dating.

At the time of their split, it was Rossdale who was being fingered as the bad guy (there’s always got to be one, right?).

Over the 20 years of their relationship (and 13 years of marriage), there were numerous tabloid stories of Rossdale’s indiscretions, one in which he allegedly cheated with someone at the Playboy Mansion just months before the couple wed.

Now, though, it’s Stefani who’s the dastardly cheater.

According to TMZ‘s “source”, which in the absence of any description we’re assuming is a magic eight-ball, Rossdale reckons Stefani took up with Shelton before their split.

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.

TMZ also asked the eight-ball what Rossdale thinks about Stefani’s new heartbroken woman scorned song Used to Love You, and it informed the site he’s “scoffing” at the lyrics and that his love was quite enough for her for many years.

Watch Gwen’s excellent sad-face, below… Post continues after video.

Radar Online has its own eight-ball, which is saying that Stefani broke it off with Rossdale because he was being predictable with the nanny.

“They were extremely flirty with each other and would go for long drives, alone. There were text messages that Gwen also found on Gavin’s phone that she thought were very incriminating.”

Meanwhile, Entertainment Tonight has noticed that Rossdale is still wearing his wedding ring. What does that mean? If only we had our own magic eight-ball.