Quote 4
As long as both she and Rudy lived, she would never kiss that miserable, filthy Saukerl. (9.9)
Liesel does change her tune, but doesn't reveal the change to Rudy, until it's too late. The fact that she never kisses Rudy when he's alive will haunt Liesel for a long time to come.
Quote 5
He must have loved her so incredibly hard. So hard that he would never ask for her lips again and would go to his grave without them. (44.42)
Rudy's premature death keeps Liesel and Rudy from ever truly discovering whether their love is confined to friendship, or whether it extends into the romantic realm. We are sure it's a romantic love for Rudy, at least in his imagination, but he's only fourteen, with much more to learn and see and grow.
Quote 6
They hugged and cried and fell on the floor. (87.4)
This is a moment from the end of the novel, when Max and Liesel reunite. We don't know what happens to their relationship after this, but we can be sure it has lots to do with love.