Does the same thing happen to her when another man goes down in her?

You should see a Dr. Thrush is a form of oral fungus,called (Candida Fungus). Every one has it at all times during their life,but something is causing your to be active and your transfering it to your wife, causing her to get yeast infections. Could be that your taking a certain medication that may be causing it to flair up. Thereare a ton of reasons that you may be able to resolve your self. Google (What is thrush) there is a ton of information about it there. Im not a DR but do have some experiance with this from when I was maried and had kids. Good luck