what did Liesel realize when she found Rudy's body after the bombing? How did she attempt to reach him?

The bombing alarms go off too late and Himmel street is bombed. Liesel is the only survivor because she was writing in the basement. She finds Rudy's body and discovers that he is dead. She confesses her love for him and gives him a Kiss. Perhaps it is a futile attempt to reach him but in any case, it is a kiss that he had always wanted.