Thomas Aquinas taught that God loves a rock with the same intensity as He loves a baby. Cardinal Ratzinger doesn’t agree with that opinion. I didn’t say he thought we were necessary absolutely. However, to be desired with eros implies that we are something to God, instead of Aquinas’s position which says God has no relation to us as we do to Him. If God IS His knowledge, then knowledge of us would change His nature, since we are contingent. But if we are nothing to God, even Jesus’s humanity being nothing, than there is no change in God’s unity and simplicity. That is Aquinas’s side. Ratzinger doesn’t look at God the same way. Aquinas would say, however, that God’s love radiates to us, although the choice to create and even become Incarnate was so inconsequential to God’s being that it was as if it were nothing.
St Thomas specifically says that God loves some things more than others (ST, Q. 20, art. 3, 4). I don’t think it would be reasonable to assume that God loves rocks as much as He loves human beings and St Thomas was a reasonable man. This is the explanation St Thomas gives how it is that God loves some things more than others (q.20, art.3):
Augustine says (Tract. in Joan. cx): "God loves all things that He has made, and amongst them rational creatures more, and of these especially those who are members of His only-begotten Son Himself; and much more than all, His only-begotten Son Himself.
“I answer that, Since to love a thing is to will it good, in a twofold way anything may be loved more, or less. In one way on the part of the act of the will itself, which is more or less intense. In this way God does not love some things more than others, because He loves all things by an act of the will that is one, simple, and always the same. In another way on the part of the good itself that a person wills for the beloved. In this way we are said to love that one more than another, for whom we will a greater good, though our will is not more intense. In this way we must needs say that God loves some things more than others. For since God’s love is the cause of goodness in things, as has been said (2), no one thing would be better than another, if God did not will greater good for one than for another.”
You mentioned the Catechism of the Council of Trent as saying that God acts whenever we act. Do you have the citation?