Buddy, I still don’t see a reason why he won’t just let her know that’s how he feels (if that is how he feels). The OP needs to hear it. Did he not tell her he loved her? At least she deserves to know the truth (where does the question of being polite come from?) and get a proper closure. She should not be expected to get ‘the hint’ and move on on her own. He needs to man up and tell her the truth in a manner that will help her move on. He took responsibility for it (did he not by admitting his feelings and making her a part of his life) and now wants to run away/avoid. Not cool at all!
People need to speak about ‘what they want’ - exactly what they want in simple, clear words so the other person doesn’t hang on.