Erectile dysfunction and lack of desire

Hello, I am a 32 year old female with a boyfriend who is 36. We have been dating a little over a year and we were friends before we started dating. Our physical encounters were very passionate at first(some of the most intense I've experienced) but they rarely led to sex. When we did begin having sex he only achieved orgasm a few times and it always seemed as if he penis was slightly soft. I seemed to be the one who initiated sex the last few times it happened. We haven't had sex or intimate contact of any kind in six months. he won't even really kiss me, he says that a crown needs to be fixed in his mouth and he feels like it a bacteria breeding ground. I think it is an excuse because he believes I will expect more. We live together now and I have seen Ketocozonole in the medicine cabinet and I have read that this drug can cause ED. He says that he loves me very much and that I am the most important person in the world to him. He says that he is attracted to me. I have begged, pleaded, cried, and talked. At first I assumed he was cheating on me, but now I know that is not the case. I have asked him why he won't touch me and he always blames it on preoccupation with school. He just finished his degree and is beginning his master's program. He doesn't wake up in the morning with an erection and I am pretty sure he doesn't masturbate. There is no porn on the computer nor any of those sites on the cache. I don't know what to do. Insurance is an issue as he doesn't have any being in school and it seems like the tests are expensive. I know I am not the first relationship where this has been a problem, his last girlfriend left him because she believe he wasn't interested in her sexually at all. I love him very much but this situation is taking a heavy toll on my self esteem. I have acted in ways that are otherwise out of character trying to find out the "truth". I feel bad about myself and my physical attractiveness. I cry all the time. I am afraid I am going to cheat on him just to get some affection and intimacy. Out of all the things I have asked him, inquiring about Ed isn't one of them. I know he must be hurting and feel like less of a man is that is what is going on. I have read that men with ED still want to have sex, they just can't. Could it be low testosterone?