Sorry to hear you are going through this. It sounds from your post, that your boyfriend's view of intamacy is very clouded by what happened to him-which is totally justified. Have u guys thought about going to a therapist together, it may help both of you express your views of intamacy and how it affects your relationship?
It sounds like your boyfriend is really struggling with this and so are you-that now it is and will continue to affect your relationship. It also sounds like you both really care for eachother and want to get married in the future, but then that means the intamacy issue may always be there in some form-especially since it was very traumatic for him.