Unfortunately, some things don't work well when they get older. If you're still married after 38 years, I suspect he's telling it like it is. It may be a health issue that he doesn't want to talk about. Men can go through "Andropause" (use to be called "Mid Life Crisis) and become moody, have hot flashes, and be impotent. Diabetes can cause this as can meds for different diseases. Usually men are embarrassed to discuss this problem. If you can make an appointment for him to see the doctor and get a good physical. There are many things that can help him.