How do I approach the subject of erectile dysfunction with someone I am dating?

I am a single woman in my forties and about a year ago I met this great single guy who is in his fifties. He lived 3000 miles away and we connected in such a way that each time I visited him, our friendship grew stronger. The last time I visited him, he said he would be attending an event two hours away from where I live and would I be his date for the weekend? This was a huge step in our relationship as up until that point, we had not had sex yet. About a week before we were to meet, he started making all kinds of excuses as to why we shouldn't share a room. He even went as far as to ask me if I could find another place to stay. I thought the whole thing was rather odd. After I reassured him that I had no intention of sleeping with him (I lied but I thought it would diffuse the situation a little), he calmed down and booked a room with two beds in it. When we got back to the room the first night and got ready to go to sleep, he climbed into my bed and proceeded to start fooling around with me--something I didn't think was going to happen. Whether it was a combination of alcohol, fear, stress, medication or just plain age, he was not able to perform the first night. He made up for it in many other ways though. I thought maybe he didn't want to have intercourse yet so I shrugged it off. He apologized in advance for his snoring, which after listening to it for hours--I realized he probably has sleep apnea. He didn't sleep well at all. That evening set the tone for the rest of the weekend. The next day, he was very grumpy and in a terrible mood and that next evening when we got back to the room, he wouldn't touch me. He went straight to bed stating he wasn't feeling well. I didn't see him crack a smile again until the next morning when he decided to leave on the early shuttle. It was like he couldn't wait to get away! I think I understand now why he didn't want to share a room. Obviously he has a few issues that he didn't want me to know about. It made me really sad because I'm pretty understanding and unconditional. We're all human and no one is perfect. What I feel is most important is our friendship and the connection we share. He told me he doesn't usually connect with people like this and that he's connected with me and he doesn't understand why but it is what it is and there's no denying it. It didn't occur to me until I left that his inability to perform the first night was probably causing him embarrassment and he was probably very upset with himself. We have mostly e-mailed and texted since this happened a month ago and have made plans to see each other in a few months. I am flying out to visit him. How do I approach all of this? He needs to know that our connection is important to me and that all the other stuff will eventually and hopefully work itself out. I want him to know I am supportive without embarrassing him. What should I do?