mrgoodstuff (and more recently stormrider) have dominated this thread, IMO.
I've had ED before, and I'm convinced it wasn't health-related at all. It was stage fright (related to confidence and d*ck size) and lack of attraction. Combine those and it's killer.
Not to mention real sex is not like porn. You do have to semi-work up to it, it's not just a whip out a c*ck and she sucks it until you are hard. There are some expectations there. All this to say, you absolutely MUST be attracted to the woman and you MUST be confident in your own skin (not everybody has 9" c*cks).
I've been married for 11 years. I had some ED at first because #1, I had some stage fright and #2, she wasn't as attractive as the girls I'd been with in the years up until that point. That went on for a while then she lost some weight and suddenly got super attractive to me and ED issues DISAPPEARED. I could nail her twice a day and want more.
Fast forward to recently and some of it has come back. We've gotten into a rut where I am not really comfortable with my own body (gotten a little fat) and she has gained a little weight too. This breeds performance anxiety (at least to me).
Reason I post this now is because this is day 1 of my recovery
. Now, it's possible that I'm also starting to see some health-related issues now like low T, I mean I am 38 and a little overweight. But I'm still convinced my ED is simply the reasons above as always.