I'm sorry that is as far as my knowledge goes. I do wish I knew more. I can only learn so much at a time.
What I'm trying to say is that the brain responds to sex by releasing hormones that cause affection, pleasure and reward. When that's gone I think we want more and more and more and more and more and more and more, etc, etc. I think we grieve for it, long for it and that may cause some suffering, as in The Gawd's situation. Grief is suffering. I bet he still remembers the way she smelled, the touch of her skin, every little detail about his lost love. That's all he thinks about, right? That's why he can't focus on the other stuff.
My sincere condolences Gawd. I can only say it does get better with time. You have to try and focus on just doing little things, make your bed, brush your teeth, wash your dishes, mow your grass, trim the trees. It will get better.