If I were to distill it to the simplest statement, maybe like this:
IF God is love, He didn't become love, He always is love. If God created the Son, then He hasn't always been love, there being no object for that love, therefore He changed, to become loving, with the 'creation' of His Son.
The Constancy of God is our single anchor. From Malachi, I like the way He puts it here, "I the LORD change not, therefore you, O Jacob, are not consumed!" Our safety in His hands is in His constancy. He never changes. He is always Who He says He is, and in Christ, He is our Father also.
The character, or nature of God, is supreme over all. Therefore any idea that God might grow or change carries with it the idea that God somehow was "less then" and now is in the process of "doing better". But that's not God. Knowing the constancy of God, we can know that Jesus was not created, but is co-eternal with the the Father.
Much love!