Explain how the death of Curley's wife further developes Steinbecks theme about what becomes of broken plans

The death of Curley's wife essentially brings George and Lennie's dream of a farm to an end. George knows that the men n the ranch will be out for blood: Lennie would not escape death or being locked in a cage forever. This certainly speaks to the quote:

The best-laid plans of mice and men often go awry