It all depends on how disproportionate the sex drives are. If they are quite different than it will forever be a sticking point.
A relationship can survive without sex. If both partners can find a way to deal with their sexuality. Oral as you provided for example. It is hard and only really strong relationship tend to survive this.
My story. My girlfriend had a similar issue,
read about it here, and things had gotten better. There were communication issues in the relationship, but lack of sex was the other reason it fell apart. It hurt her, 1 or 2 on a scale of 10, and because of the fact it will hurt and the fear that it would hurt, she had no libido. I figure you're probably in the same boat.
I don't have good news, we broke up a week ago.
I view sex as a large part of a relationship. If I am not getting it then there has to be a good reason why not. This is my opinion and my view nothing else. The hard part here is that the door was open for two years and now it has been shut for three. It is hard to go from regular to nothing. It is almost better to start at nothing and stay there so that they is no expectations.
Advice: This is a hard one. Communication. Beginning to end. Make sure he knows that you don't want to do anything. Making concessions to him will work, but don't let him bully you into it. Only do what you're comfortable with. There are other alternatives to penetrations and I am sure you have encountered those.
I think seeing how important sex is to the relationship from the view of your partner is a good first step. It is a part of your relationship but it isn't all of it. She where he is and where you are. Maybe you can survive until the solution comes. Maybe not.
I wish you the best of luck.