Go with Meal Planner for Everyone!

You can't argue with the size of the target market, at least.

I feel like there's a big difference between "for my wife" versus "for wives". The former makes no assumption about the roles of other people who use it (except, presumably, that they're interested in planning meals).

Too late to edit, but I'd like to add that "for your wife" would be as bad as "for wives", outside of a context where you are talking to a specific person and you know they have a wife who would be interested.

The one downside is that many women are very proud to be housewives. Marketing to everyone in this context despecializes, considering they make up a very considerable margin of the stay-at-home parents and mealmakers worldwide.

As much as I would hate for this to be the case, in a marketing context it makes absolute sense to go after housewives.