Hi I am Gopi. I am 28 years old. I can understand your frustration. in your case the "human psyche" is playing into picture, this is my opinion. The reason is, a person remains curious as long as he has to struggle or work harder to get to some thing. In this case, having Sex. So in early days of a relation be it just BF-GF type or marriage, wherein individuals come together for the first time, it is a natural instinct to make an impression or create a domain, other way of seeing it is making a relation. This instinct will drive individuals to put more into it. WIth natural invovlement there would be more contribution to the relation. This relation can be "Sex". Once individual reaches a state of "Loss of interest" or "No challenge" or "easy availability" he/she would loose interest. This plays more in case of Men because, by nature men like to be teased and challenged. So, please dont be disheartened by this set back. Perhaps His work life or life outside is bothering him much. Try to be a supportive partner and try to lure him and make him work for getting it. This way you will keep your man, chasing you and this relation will last longer, sometimes a life time.
Ever seen a happily married couple, in thier late 70s ?? still keeping healthy sexual ties and bound with passion ??
Approach this problem naturally and scientifically.
HTH
Dexthor.
