Has Bill Been Knowing Mike Hasn't Been Moving On?

Now, as we jump to the scene where Tina is shocked by the cardboard monsters, Mike tries to explain, but she drives away. Cam asks why she hates him, and Bill explains that Mike hasn't been moving on, only for Mike to scream "Do you mind?!" Defying by this stigma, Bill somehow knows Mike is grieving Carol's death. So, how does he know that Cam's dad hasn't been moving on?