Why did God create humans and the universe, as nothing adds to his love or happiness?
So that we could have a share in His eternal life and happiness.
As a Catholic I can only go as far as Hans Urs von Balthasar.
There is evil, horror, and hate in this world; what makes you think that evil, horror and hate does not exist in the spiritual world?
I cannot see how a good God would create a being who will suffer for all eternity, especially if that person had a morally good life, except for one unforgiven mortal sin.
The cosmos is made up of systems governed by laws. Even we are made up of systems; Skeletal System, Nervous System, Muscular System, Cardiovascular, Reproductive, Digestive, etc. All of these systems are governed by the laws of health. A little poison can ruin and destroy the entire system. Likewise the economy of the soul exists within a spiritual system governed by spiritual laws, known as the Ten Commandments. our Life of Grace is the life of the soul. We break those laws, we can kill the life of grace within us.
On earth we live in time where we can choose between good and evil; we can repent and amend our ways. Once we die and our soul separates from our body we enter the spiritual eternal realm where we cannot change our state. Either we have the life of grace in us in union with God, or we are forever separated from God, the result of our own deliberate actions while on earth.
Jesus Christ sacrificed himself and died a horrible death so that we could be saved. Salvation was not cheap, it cost Our Lord His life and blood. life is not a game, we don’t play with fire, we don’t drink poison, we avoid things that harm us. Likew]wise for the soul. The body is temporal. Where the soul is eternal.
The fallen angels were created good and they demonized themselves when they rebelled against God. Likewise, man is called to be sanctified, but he is free to demonize himself by rebelling and rejecting God.