@dpproblem - I'm almost 60, and have had issues with ED, but they have been mainly psychological, not health or age related, but I will say that the more a man has issues with erections, the more issues with erections he will have...
It's very much a vicious circle, and can be difficult to break. The good news is that he's seen a GP, and that there is nothing obvious wrong. Did he get a testosterone test as well? If not, it might be worth him asking for one.
He probably feels a bit of a failure - it's sometimes a difficult thing for a man to accept that he's not 20 any more..
My personal experience was that I didn't suffer from ED issues until I was in my late 40's, but it coincided with my XW's menopause. I believe the two were related!
Whilst it might be a good idea to be more assertive in the bedroom, it is also a good idea to talk to him. If he is stressed or feeling down, he needs to tell you, he needs to share it with you.
Is there a pattern to his stress / moods?
Somehow you both need to work on making him NOT feel a failure - maybe take PIV off the table for a while. Focus on other things, like just touching and stroking each other, mutual masturbation / oral - maybe get some toys for you to share. if he gets erect, fantastic, move things on (try a cock ring). If he doesn't, or loses it, tell him not to worry about it, but to carry on with what's happening - try to get him back in the room, by focusing on you, rather than his lack of erection.
As for your lack of confidence, it's partially at least related to his apparent lack of desire - "does he fancy me any more?" If you worry about things like that, he will pick it up subconsciously, and it will affect him, which will affect you....
Treat yourself to some lingerie, or something that makes you feel good / sexy - who knows it might be the thing that turns the corner for you! Good luck!