Yes, yeast infection could do this. The best clue will be whether the problem continues after her yeast infection is treated. If so, it could mean something else, e.g., you could both be carrying strep, staph, or other bacteria; or conceivably an allergic reaction to your wife's vaginal secretions. (Not common, but sometimes happens; and can first appear after several yearss.) In any case, if the problem persists, see if washing with soap and water soon after sex prevents it.
Good luck-- HHH, MD
As I said in the original post this has been a recurring problem and I have taken to showering immediately after sex and even going so far as to put an antifungal cream on areas I thought may have been affected after showering but this has not seemed to help. I thought this additional information might be pertinant and I am wondering how best to treat this rash if it doesn't require medical attention.
Sorry, I can't get into specific treatment advice in an online forum--that's the job of your health care provider. See him/her if what you're doing isn't helping.
Regards-- HHH, MD