I don't remember who said that every child is a former angel who descended into the world, so they have a pair of clear eyes that can see the sins and all unclean things in the world. Since you were once an angel, why do you have to go to the human world to endure the pain of birth, old age, illness, death, and reincarnation? Every time you end a life with regret, you have to start a new life with full of unwillingness...
Because every angel has heard that there are things in the world that they hope for but dare not touch...