This is such a common scenario for women who are approaching the menopause, believe it or not! The hormonal changes going on can affect libido, mood, and physical and emotional health and many women, especially if they are used to being strong/independent can find it very confusing and sometimes scary.
There are several remedies that she could try, Maca is traditionally used to help balance the hormonal cycle, improve libido and raise the mood so it may be worth her trying this for a few months to see if it helps. Look for the tablets or capsules, because powder or granules will not be strong enough.
I would also suggest a good high strength multivit and extra magnesium as this hormonal shift can stress the body physically, causing further symptoms. Acupuncture can be very effective for this and is well worth looking into. This period of change can last for several years so it is important that she starts to support her physical and emotional self. It's great that you are trying to support her in this so don't give up!