He supported her.

All these words fell like a jug of ice water on Prince Harry, for he was deeply disappointed that not even his brother supported him. He loved Meghan and disagreed with William. But Enrique wasn’t going to let them keep talking bad about the woman he loved, who also had to deal with his family problems and the distrust of the Royal Family and the English people.
Even His Family Against Him

Not only did the Royal Family criticize Meghan, but so did his own family. Just like someone was going to trust her. Meghan received adverse reviews everywhere. Her father Thomas Markle and stepsister Samantha seem to have things to say about her on TV shows, too, so they seized the moment and threw themselves without thinking of it as poisonous snakes to say everything they came up with.