Communication is a great way to start for both of you-
I think you may need to see if she has some underlying medical condition that has decreased her libido. Stress and fatigue can greatly diminish your sex drive. If it is stess induced then maybe looking in to relaxation therapy or meditation. She could be depressed which can lead to low libido. Also, look into nutrition and exercise. I know when I am doing my 2 mile cardio alone it boost my mood and increases my libido. Our lives are full of stress and sex should not be one of the stressers it should be enjoyable and relieve tension. So in short, nutrition, exercises and adequate rest. Learn relaxation techniques, meditation and/or yoga to deal with everyday stress.
I was searching the internet and found this interesting article which that lifestyle changes can be benificial, that is eating right, exercise, adequate rest -
Low sex drive in women - MSN Health & Fitness - Women's Sexual Health
I recommend books by Dr. Andrew Weil's to get you started for a healthy life:
Amazon.com: Natural Health, Natural Medicine: The Complete Guide to Wellness and Self-Care for Optimum Health: Andrew Weil: Books
Amazon.com: Dr. Andrew Weil's Guide to Eating Well: Dr. Andrew Weil: Movies & TV
In short, see a physician to make sure it is not medical, follow the nutrition, exercise, rest and relaxation techniques and you can seek a therapist to help with some of the emotions that you and your wife are experiencing.
Just my opinion
Good Luck