Warwick's attitude to the Wydevilles started the previous year - when Katherine Wydeville married the duke of Buckingham. Originally, Warwick had wanted Buckie for Isabel/Anne. Then the Wydevilles came out of nowhere and started snapping up all the available grooms.
Unfortunately there was a strong psychological aspect to Warwick's change in attitude: Warwick's dad joined Richard of York's rebellion because there was difficultyover rival claims to an inheritance with the duke of Somerset. Henry VI sided with Somerset, and Warwick, feeling that the only reason Somerset "won" was because he was "related" to the king, not because he was the best claimant.
Now, see it from Warwick's POV how the Wydevilles have done nothing to merit this advancement beyond marrying the king (there would've been an aspet of humiliation for Warwick in seeing a reminder like that as well). And suddenly the Wydevilles are everywhere. Including in Warwick's own family by marrying his aunt, the duchess of Norfolk. There was a concern at the time, due to the fact that the then duke of Norfolk was 25yo and without a male heir, that should something happen to Norfolk, the Wydevilles would claim the dukedom (and possibly, get it, remember, Wydevilles are the "new" Beauforts).
But there was another angle to it as well. From Warwick's former warder and father-in-law: the 13e earl of Warwick. The man had been captain of Calais. He was removed from that post (without warning or chance to defend himself) by the duke of Bedford. On the word of three men (Lewis John, Richard Bokeland and Richard Wydeville). The biggest "contributor of evidence" was Wydeville, Bedford's chamberlain. 13e Warwick was apparently bitter about being fired and blamed all of it on these three men. So the Wydevilles are already persona non grata to Warwick's wife. Now Warwick himself has been humiliated by them (Liz Wydeville's marriage to Edward caused Warwick some loss of face as a diplomat), and worse is that he's essentially forced to watch as the king he put in place, never held back for, gives stuff to other people and repeatedly deny Warwick's "hard earned" (as he likely saw it) and "well deserved" "rewards". His little brother gets made a "marquess" which means Warwick has to walk behind him, and his nephew is a duke, which means that, with the exception of Buckingham, Norfolk, Suffolk and the royal family, Warwick - the premier earl in England - has to now kowtow to a child. And I don't think Edward would've been above being deliberate in his choice of title for the boy (perhaps getting a good chuckle every time "the earl of Warwick" had to yield to the "duke of Bedford"). In short, I think it was a case of "if it hadn't been this, it would've been that".