From what you say it seems that there is quite a lot of stress in your lives right now. That can be a great contributor to low sexual desire for both partners.
There may also be some hidden resentments and anger that manifest in denial of intimacy. Something that is no longer even worth arguing about because it will never change perhaps?
Most certainly, he should get checked out for any physical causes of low sex drive as there may be many other causes such a low testosterone levels, prostate gland problems, high cholesterol levels, thyroid issues, etc etc.
Here are some suggestions, with links to explore:
"Loss of Libido
Over the course of a man's life, stress, illness, medications, emotional problems, or reduced levels of male sex hormones can result in loss of libido. Also, at times, your interest and desire for sex might not match that of your partner, which is normal in long-term relationships.
Talking frankly with your partner and your doctor about sexual problems or loss of libido is the first step towards restoring sexual health."
from:
http://www.4woman.gov/mens/sexual/impotence.cfm
"What kinds of medical conditions can cause problems with sexual health?
Any condition that affects general health and well-being is also going to affect sexual function. Illnesses that involve the cardiovascular system, high blood pressure, diabetes, hormonal problems,
Depression or anxiety — and the medications used to treat these conditions — could pose a potential problem for your sexual health.
Your blood pressure, for instance, could affect your ability to become aroused, as could the medication you take to treat high blood pressure. For a man, this might mean difficulty in getting an erection. For a woman, it might affect how her clitoris engorges.
What people often don't think about is the emotional effects of having an ailment. After a heart attack, for instance, you could become depressed because the experience drove home the fact of your mortality. One of the symptoms of
Depression is the loss of pleasure or sexual interest. So even though the heart attack itself may have no direct effect on your sexual functioning, your emotions may disrupt it. "
from:
http://www.mayoclinic.com/health/sexual-health/HA00035
"Herbs which are useful in loss of libido:
Safed Musli (Chlorophytum Borivilianum):
The dried roots of Safed Musli (also known as asparagus) are used in Ayurveda as an aphrodisiac.
Primarily used as a tonic and rejuvenative for the reproductive system both for men and women. The regular use of this herb is valuable in impotency, loss of libido , premature ejaculation & low sperm count in men & women.
It is also useful during pregnancy as a nutritive tonic for mother and fetus. Post-partum it replenishes lost fluids, prana, ojas and improves the quantity and flow of breast milk. Used in chronic leucorrhoea.
Ashwagandha (Withania somnifera) :
The herb helps to cure female sterility. Powder of the roots can be taken with milk for 5 to 6 successive nights after menstruation.
Two to four grams of root with milk or ghee can be taken as an aphrodisiac to enhance libido. It is also beneficial for the treatment of spermatorrhoea or involuntary ejaculations. Two to four gram of powdered root can also be taken daily with sugar, honey, long pepper and ghee in the treatment of these conditions.
Shilajeet (Asphaltum) :
It is well known that Shilajeet would return the libido of people to a level of teenagers. Shilajeet increases the core energy responsible for sexual and spiritual power. The use of Shilajeet for renewing vitality.
Garlic:
Garlic is one of the most remarkable home remedies in the treatment of sexual disorder & loss of libido. It is a natural and harmless aphrodisiac. Garlic has a pronounced aphrodisiac effect.
Drumstick:
A soup made with drumstick flowers boiled in milk is very useful as a sexual tonic in the treatment of loss of libido. It is also useful in the functional sterility in both males and females. The powder of the dry bark is also valuable in impotency, premature ejaculation and thinness of semen. Powder of the dry bark should be boiled in half a liter of water of about half an hour. Thirty grams of powder, mixed with tablespoon of honey, should be taken thrice daily.
Ginger:
The juice extracted from ginger is a valuable aphrodisiac and beneficial in the treatment of loss of libido. For better results, half a teaspoon of ginger juice should be taken with a half boiled egg and honey, once daily at night for a month. It is said to relieve impotency, premature ejaculation and spermatorrhoea.
Diet:
Diet is an important factors, to begin with the patient should adopt an exclusive fresh fruit diet. Take fresh fruits and fresh fruit juice twice daily. Concentrate on foods like nut, cereals , some green vegetables, fruits, milk, honey etc.
Avoid smoking, alcohol, tea, coffee all processed canned refined and denatured foods especially white
Sugar and white flour and products made from them.
from:
http://www.allayurveda.com/topic_month_august2006.htm
"One technique that may be helpful is to take the focus off of sex and shift it to sensuality, engaging in massage and nonsexual touching. The purpose is to take the pressure off and enjoy the sensations, rather than focus on an end result.
Improving communication patterns are important. Don’t bottle up anger and other emotions, but also learn how to express them in a respectful and productive manner. Don’t be afraid to agree to disagree, winning or being right is not always the most important thing. Choose your battles well, and weigh them against the value of the relationship itself. Do not argue in the bedroom. And, sometimes, a relationship just is not meant to be. This is something that must be accepted. Sometimes, it is just time to move on.
A loss of libido is about much more than just sex. It is a signal, a sign, and it should not be ignored. Do not spend too much time trying home treatments. If these do not bring noticeable improvement, seek professional care. For the vast majority of men, a loss of libido is highly treatable."
from:
http://www.essortment.com/lifestyle/losslibidomen_swex.htm