There must be some reasons for his aversion in relationship but difficult to judge what it is from your short mail. Don’t you have any slightest idea about it?! Just think over it, you may find some clue. There must be multiple reasons grown over a period. Possibility of an affair may not be ruled out. You may involve some one to whom he respects or close to both of you. You may directly ask him about his aversion, I’m sure you must have tried number of time. Until you know the reasons, it is difficult to go ahead.