Just for those who think Joe was double crossed by his wife

Right at the end of the movie Hackman makes a comment to her once Jimmy is in the car about how the plan is as cute as a Chinese baby and then it seems like he receives a little nod from her. Earlier in the film Pinky and Bob have a conversation in the car with Jimmy, where Jimmy is asking all these questions and they bring up the Chinese reference in this context with the meaning going straight over Jimmy's head. It seems like another conversation designed purposefully to go over Jimmy's head. Like Joe is telling her not to worry because the plan isn't broken yet.

Way I see it this could be for one of two reasons:-
1) She will leave Jimmy and meet up with her husband.

2) They never had a very pasionate relationship the whole way through the movie, they appear more like casual partners than a married couple. It may simply have been a relationship of convenience in which case by planning it this way it left his wife looking in the clear when Jimmy discovers that he doesn't have the gold and thus enables her to continue with her life or her trade without Jimmy causing trouble for her.