Some of the reasons for women's drop in sexual desire many times deals with some emotional trauma, stress, or exhaustion.
Sometimes men expect their wives to work a job in the workplace, and then come home and be the housewife of the 1950's. I know several men, as well as read many post on Dr Phil's boards where the man thinks it's the wife's place to cook, clean the house, and take care of the children, after they get off from work. This can cause exhaustion and with that the lack of sexual desire.
Stress can be a major factor for either sex to drop in sexual desire. The expression, "If Mama ain't happy, no one's happy," has its roots in truth, and if she is stressed out, sex may very well be the last thing on her mind. Stress can come from things not being good at home, work, or with outside family members. Stress can kill people much less sexual desires.
If some emotional trauma has occurred, such as infidelity, women will find just as difficult to become intimate again, as do men, when they have been offended.
True love travels on a graveled road, and when one truly loves their mate, they should be willing to take the bad with the good. Communications is the cornerstone of any relationship, and what ever the problem is that is causing the drop in sexual desires, should be addressed as soon as possible. If the above things mentioned are not factors, then maybe a doctor should be consulted, and hormone levels checked, medications that are being taken should be looked at to see if this could be a factor even if it is a small possibility. There is a certain acid reducing medication on the market that is by prescription as well as OTC, and one of the rare side effects of this medication is anxiety. I talked with my doctor about a bout of anxiety I was going through a few years ago, and he didn't think any of the medications I was on could cause this. One night about three o'clock in the morning, I was up and having a major anxiety attack, and was trying to think what was different in my life. I just happened to look on top of the fridge, and noticed my "new" heartburn medicine sitting on top. I got out a PDR, (this being before the Internet was available to the public) and there listed as one of the rare side effects of the medicine, was anxiety. I was anxiously relieved. I quit taking the medication, and within a few days the anxiety subsided. So my point being, you may want to check any medications that are being taken on the Internet as well as talking to your doctor, as sometimes they may forget about the rare side effects, and you may just very well be one of the unlucky ones, that some medication is causing this effect.
I hope this helps. Good luck, and I hope you soon are having great sex.