How to increase husbands libido?

We have been married for over 23 years and have 2 adult children. He is 46 and I am 48 we both work full time. Our sex life has slowly dropped off over the years to the point we have sex maybe once a week or once every 2 weeks. While his libido has dropped off mine has ramped up. This ramping up seemed to start about 5 years ago when had my hysterectomy. Had it done because of sever fibro problem that caused immense pain each month. Since then no more pain and a increase in libido. My husband on the other hand has had a decrease in his libido but not related to that time frame just has decrease over the past few years. Even when have dressed sexy and tried to initiate sex more often many times he says is too tired or when have pushed forward has stopped part way because of loss of erection. Thought maybe he has a ED issue but he has seen doctor and when we do have sex its almost like when we were both first married/younger actually has even more staying power and energy then when we were younger. So the one time a week is more intense and longer but want it more often. Looking for suggestions on helping him or helping us have sex 3 or 4 times a week even not even more. I understand partially why he is more tired about 2 years ago he had lost his job when economy started to go down hill was out of work for about 6 months. He now works at a job that had done when was younger before went back to college. Its more physically demanding then his engineering job that lost but it actually pays better if can believe that. Think because of his skill and knowledge they pay him more but its more physically demanding meaning he comes home tired more often. Some days he does not but many times he is just worn out at end of those days. Especially when some days are 10-12 hours while others are only 6-8. Might say just try on the 6-8 hour days which is the times have tried to sneak in a extra.