Opening a line of communication is by far the most important thing to do at this point! It won't be easy, but will be the only way to make things better. First of all, approach him in a supportive and understanding way. Researching erectile disfunction and being aware can help you through this.

I am not totally familiar with ED, but I do know that when someone starts out with slight hints of ED, the anxiety and fear can build up and make the ED worse. Getting your feelings out in the air will gradually help him to feel more comfortable. I am certain that he knows it's on your mind already, so it shouldn't be a suprise to him. The open line of communication will probably greatly reduce the anxiety of the situation.

I would first start by reassuring him that you care about him and explain that you want to be able to talk about your sexual relationship more. Kind of ease him in. You will have to be honest about how you are feeling, what you need, and that you want to try to find ways to help the situation. He may or may not take it well, but it must be done if either of you are ever going to be satisfied.

He may need more to get going. Try to get him to tell you some things that turn him on that you haven't tried before. Some men need therapy to work out anxiety issues. Or, some men just have a medical condition which prevents erections in which case he would need to see a doctor for medication.

There are solutions to your problem. Talking about it is the first step. You just have to be brave and go for it. Remember... gentle and understanding.

Good luck!