I have been in a similar scenario in my past..he was a good man, but didnt show much affection or interest in sex...after 2 years of trying to talk/scream and shout about it, I gave up and ended the relationship...he was devastated and desperate to come back, it was too late for me...but one thing I did learn from it was how much he did actually love and want me, but I had felt rejected for far to long and made my mind up that this wasnt what I wanted in my life, I needed attention and just wasnt getting it...I dont regret ending it, in fact im glad I did, cos it just wears you down and leaves you with not a lot of confidence.
I dont understand why he would say you dont turn him on, he must have seen something in you that attracted you to him in the 1st place!!! I think the problem is not you, but him, I think somewhere along the lines he has issues regarding relationships and sex, only he knows what they are and maybe you should try getting to the bottom of it. He sounds good in every other way, just the "issues" is the problem, the fact that he cant get an erection at times spells out to me he is feeling inadequate about sex....I think maybe he talks to you the way he does as a way of taking the blame off of him and making it seem as if your the problem...dont let him do this as it will damage your confidence!!!!