Why has the Eighth Prince renounced the world?

His wife has died, and he becomes jealous of the birds and how they able to dance about, content with the way things are. He wishes that he could be like them. He once had a happy and frivolous life, but age and his wife's death have changed many things. He decides to renounce the world, yet he cannot renounce it completely because he still needs to care for his daughters.