Catholic doctrine does not contradict "God is love" it is the fullness of it!
Of course God knows we can't be perfect! But He also knows that we can strive to be.
That reality leads to a logical contradiction.
-God is love.
-Thus God wants to be united in love with His creation.
- creation cannot be God this is not perfect
- nothing imperfect can be united with God
Catholicism is the story of God making up the difference for us, so we can be united to him. But as you said, it is our choice, which God respects.
The church exists, not to come between you and God, but to provide a highway for you and God to come together.
The visual I have is that people look at the church and see a bunch of stones blocking their way. "Look at all these stones" why erect a wall between me and God. But if they lift their eyes from their feet they will realize that it is not a wall, but a smooth road straight to God. All those rules are there to bear your weight for you, not to get in your way.