When do you draw a firm boundary around your communication with people who are not looking for a relationship (with you)?

I have been guilty of projecting my desires for dating onto people who have initiated contact with me regularly, but that don’t want to go on dates or do anything leading to a relationship. The conversation is enjoyable and can fuel a fantasy for more. Just wondering how others deal with communicating with those who don’t want a relationship (with you) - do you engage without expectation because it’s purely enjoyable or do draw a boundary with yourself and stop participating in communication with that person?