in order for you to do this you have to learn to love yourself fully, and become independent of him. Get a hobby or go out with your friends without him break away from him and do healthy things every once in a while if you do this you will learn to be less clingy because we are usually this way because we are afraid to lose that person, you will go out and do things on your own and you will come back and he will still be there. You will begin to trust more in yourself and your confidence will build and that will be more attractive to him