So lets frame this picture differently.
You have a young child whom you lavish attention on, spend hours with the child simply adoring it and making sure he knows that all of his needs are your priority, he feels like the center of the universe in your home. He enjoys his friends when they come to play, but always looks forward to time when its just you and him.
You decide to have another child and suddenly the older child is acting strange. You try to help them both feel happy in your home. But your older child is pouty for hours at a time, and upset when the other child tries to be with you. Your child is refusing to eat, doesn't even want to be in the same room as the newbie. So you try even harder to help your older child feel special but he just isn't having it.
I am going to let you sit with this and see what answer you find....