Reasons for his disinterest can be many. Most of the males are not sensitive enough to mix their dislikes with sexual life like females. Surely, his reasons might be beyond his dislike for your mother. Only way to make him think about it is to stop craving for it. You need to show him that you are also comfortable without it. At the same time, do everything to look & smell good and to attract him subtly. Avoid hot emotional arguments. Stay in positive mood all the time. Do not nag him for anything. Do not go out of the way to please him. Make sure that he does not have a fling somewhere (need not to be suspicious but just to be vigilant as a part of solution). Patience is the key.