Apathy is hard to live with. I have had this problem many times, where I just turn off on someone. My counselor said I was scared and avoiding intimacy but I'm not sure if that is it. After a while, I just start to lose interest. It's actually happened to me many times, so I know there is a pattern but I don't really know what it is. I'm 62 so I've had a lot of experience.

But in staying in the relationship you are not really being fair to him or yourself. You might want to consider letting go. Just my opinion so don't take it too seriously.