There are too many comments for me to read, so I apologize if this has been said already.

You were extremely patient and understanding with him for an entire year. An entire year. You consistently put his needs ahead of yours, yet he never even considered yours. Or, he didn't consider them more important than his own ego (since he claimed he didn't go down or finger you because he didn't know how). He had an entire year to try to do something, or to try to get his ED issues resolved, but he didn't. Did he even want to get them resolved? It doesn't seem like he did.

However, as much as I hate when people throw this out there as a possibility when two people aren't sexually compatible, I have to wonder if he might be gay, or he has some issue with female genitalia. He had no issues with you focusing on his penis, but he couldn't do anything when a vagina was involved.

Regardless, no one can blame you for growing resentful at being neglected. The beginning of a new relationship is full of excitement, and that usually keeps issues from seeming to be big problems. As time goes on, and the rose-colored glasses come off, things that slightly bothered us bother us a lot. So, not only is he probably not as "entirely lovely" as a boyfriend as you currently think, but the sexual incompatibility would have driven you insane in another year or two. He had no plans to address the situation, and he knew you weren't getting any pleasure from the physical side.

How do you avoid this mistake in the future? What you've experienced with this guy is not common, so it's unlikely that you will face another partner like this. If you do, you communicate, communicate, communicate with him. If he doesn't seem interested in resolving the issues, you end it.