Are you and your wifes itunes on different computers?
Then Home Sharing works as advertised
1) Authorise each others machine with the other persons Apple ID (Store > Authorise this computer) This will not affect playing of any existing content but will allow you to play the other persons content once it is on your machine.
2)File > Home Sharing > Create Home Sharing. Enter the same Apple ID for BOTH computers.This is essential
3) When you have created the home share you can click on the other persons library shown about halfway down in the Left Hand Sidebar ( View > Show Sidebar)
4) Select what content you want to copy and click the Import button bottom right. It only activates when you have made a selection
5) final step if you want to enable automatic copying of new music, movies whatever click on the settings button and select what categories you want to automatically transfer new purchases for