Question ——–Why did the Word become Flesh  ?   Why did God become man  ?

The Catholic Catechism gives 4 answers to this awesome question

1. He wanted to save us by reconciling us with God who loved us and He sent His Son to be an expiation for our sins.
2. So that we might know God’s love.  God so loved the world that He gave His only-begotten Son, that whoever believes in him should not perish but have eternal life.   St. Thomas Aquinas tells us that God could simply declare our sins forgiven–but that was not enough for him.    He wanted to show us  that he loves –so he becomes man and goes to the cross  to prove to us how much he loves us.
3. He wants us to love him in return. That is what lovers want from each other–and God is the source of all love. To be our model of holiness
   

   “love one another as I have loved you”

   He not only wants to show he loves us but wants our love in return.  Love is a two-way street, a two-way relationship.  That love implies an effective offering of oneself, after his example.   We are to love the Father as Our  Lord loved Him.

4. To make us partakers of the divine nature. For this is why the Lord became man, and the Son of God became the Son of Man, so that man, by entering into communion with the Word and thus receiving divine sonship, might become a son of God.
   

   “The only-begotten Son of God , wanting to make us sharers in his divinity, assumed our nature, so that he, made man, might make men gods.”

   St Thomas Aquinas

To put it simply, he wants to share His happiness with us –something remembered at every Mass when a drop of water is mixed with the wine in the chalice.