My experiences had nothing to do with SPs. But after my dad died back 15 years ago or so, I was quite down / blue for many many months. I won't say depressed, because although people said I was depressed, I chose to make the distinction between sorrow and depression. The 2 are not the same. But at the time, I lost interest in sex and nothing gave me any pleasure or joy. Or even contentment for that matter. I felt bad all over. I would think that I wanted to get laid, or that I should get laid, but there was not that usual body cramp that I would always get in anticipation of sex.. I would get semi wood, maybe 30% or 40% of what was really needed and I would try to jam it in. I definitely could not maintain wood. It was all very disconcerting to me, someone who had always been very driven and LOVED sex.
I think that you need to be hitting on all 8 cylinders in life in order to really get into sex. You can't phone it in. When you're on, and you're healthy, and you're content, then your dick will do what it's supposed to do with gusto. It's like your cock is some sort of litmus test with respect to everything else that is happening around you and with you. When everything is good, you're cock is good. Throw a wrench into life's machine and the first thing that jams up is your cock.