Everything in this time of the United States was difficult to get. So having a delicacy like ketchup was incredible scarce to come by. That's why Lennie always wanted the ketchup according to George (Steinbeck). And Lennie ended up saying he would let George have the ketchup because he was sorry about George yelling at him. So George apologized and showed that George cares about Lennie, and was the rock for the group. Saying he would do what's best for Lennie.