Answer:
Lennie accidentally killed his pet. These foreshadowing moments establish Lennie's innocence and make his tragedy seem inevitable. Lennie's passion for stroking soft objects and his tendency to kill them are established when he kills Curley's wife. The reader doesn't think Lennie could premeditatedly kill.
Step-by-step explanation:
This is just my own opinion. Of course, you are free to alter it to your own.