OK...and here's a completely different angle on all this because I LIVED it.
Have your WS get a physical and get his heart checked out. FWS was having "issues" (cough, cough) with his performance and his doctor, me and him all blamed it on the after-effects of his affairs.
Come to find out it was his heart. He died from what's called "The Widow Maker". Major blockages in both veins. Hindsight we should have insisted on a more extensive check of his heart but we didn't read the warning signs right and thought is was due to guilt.
Having problems with being tired all the time, and desire/performance issues are indicators there isn't enough blood moving through the body.
Please.....we all like to blame everything on sex and mental issues but heart disease can play a huge part in this. Get his heart checked.