Everyone goes through ups and downs with sex but I would be very concerned if the man of the relationship did not want to have sex. It is just not typical.
I would first wonder if he has some sort of medical thing going on. If that is the case there are different avenues and meds available that can correct the problem.
The counseling option is a viable idea as well, married or not, it can be helpful in many ways. The sex thing may be stemming from something else.
The last thing you need to think about is the long term consequences of letting this go. Although you feel intimately satisfied, sex is still a big part of it. The satisfied feeling will go away because it never goes anywhere.
One thing I have learned as I get older (just turned 40) is that as you begin to lose that perfectly unwrinkled skin, your body does not sit as it once did, etc. you really rely on your partner to be there, love you, and show you that you are still the most beautiful thing to them. There is something to be said for a man that can take your insecurities and turn them into desire, love and romance. It gives you a sense of beauty and strength as a woman.
Please don't get me wrong, sex is not everything, in fact when you look at the percent of time you even spend having sex in a day (even the most active people) it is a very small window. It is just a very blessed part of a relationship that solidifies and molds our feelings for one another. I hate to tell you this, but if you guys are not able to correct it medically or by counseling then I would call it quits. You will regret hanging in there down the road.
Good luck to you.