So just remember what I said, be patient, focus on the relationship, build up his ego, and in a couple of months, you will be screaming his name. It is not uncommon for a man when under stress to underperform, and that can go on for years, anxiety is a killer in all kinds of ways. You said when you just started out, it was not great but good, then it can go back to being good first then great. After a while, sooner than later, you are going to be surprise about the miracle.
Reassure him of how important the relationship is to you, and if he is not even able to get it up, that's okay, you love him unconditionally. So for the time being, let him know that you are not interested in him giving it to you the way you like it, just let him know that you love him, and the 11 years that you are together means a whole lot to you. The ego is tied very closely to the p.s, not sure why that is, but the bigger and better it operates, the more confident the man is. At this point however you are going to have to exercise just a little patience and understand that you are dealing with the male ego. You are heading down a road that is eventually going to hurt the both of you.