I’m sorry you’re in so much pain. Rejection hurts, and he is being very clear that he doesn’t want to be with you or marry you. My advice is that you accept this rejection and stop contacting him, so that you can heal from your disappointment and move on. For future, never chase a guy. Always let him do the chasing, and always let him propose — that’s how you know you’re with someone who truly wants to be with you. If he is the one doing the chasing and the asking, he’s going to want to win you over, and you’ll know that because it’s actually happening! 😉
Again, I’m very sorry for your hurt, but the longer you try to convince him to stay with you, the worse this will be for you. Accept the rejection and move on.