I am rather clingy myself, and I think it's something that he needs to be aware of and be able to work on himself. What really gave me some perspective was when my girl told me that she was feeling smothered and that, when she felt smothered, she tended to push me away more to try and get that space. Perhaps you should talk with him and let him know how it makes you feel and make your feelings for him clear. It will probably result in tears and be rather emotional, but hopefully it will get things sorted. In saying that, try and be understanding with him and see where he's coming from as well. If he's afraid you'll leave him, there's a reason for it, even if it's one that has nothing to do with you such as an ex that things didn't go so well with. If it continues, though, I think you should evaluate the relationship and see if the rest of the relationship is worth dealing with the clingy aspect of things, you shouldn't be unhappy in a relationship. I hope this helps!