Well, the last time Michael had the audacity to question her precious baby, he got cheated on for it. And since she has never admitted she was wrong about Fen and is still using it as justification for her affair, Michael is now put in the position of going along with it. Plus, he wants to believe it because he hates Carmine, thanks to Lauren's affair.
And if Lauren questions the truth from Fen doesn't that send the message that she is choosing her lover over her son? How can she do that when she refuses to let Michael off the hook for not believing Fen before? Sweet, innocent Jamie was an evil liar in her eyes, so how can she now defend her slimy bartender lover over Fen?
Fen is quite the little manipulator, and Gloria was right. This is Lauren's fault. She brought all of this on herself (and her husband). Maybe if Lauren had backed Michael up over the bullying situation, Fen would have gotten help by now, but instead she blamed and punished Michael for trying to hold Fen accountable.
But as far as I'm concerned, Carmine played with fire when he involved himself in someone else's family business. He thought he wanted to play daddy to Fen and husband to Lauren. Maybe he'll figure out that that is not such a walk in the park after all. Lauren turns into a nasty protective mama bear when you dare to accuse her little boy. While I have no sympathy for Carmine at all, I don't want him to go down for something he didn't do, when/if he goes down, it should be for a legit reason.