It's difficult for Liesel to love Rudy because, although he did
always tease for a kiss, Liesel just saw him as a friend. When
Liesel found Max at the "parade" and they got whipped, Liesel did
want a kiss. But her desire could've caused many conflicting
emotions she didn't want with Rudy. Therefore, that scene in the
book explained that Liesel just wasn't ever ready to confirm that
she loved Rudy.