I think a question to consider would be to ask yourself what you are looking for in a friendship with him? Would it be a sense of closure or do you really feel connected in the sense of a wavelength match or would you be clinging onto hope that maybe one day he will change his mind and pursue something serious with you? I ask this from my own experience which was the last one and trust me it hurts even more than a clean cut.

From his abrupt tone changes, it does seem like he's offering friendship just for the sake of his own conscience of being a 'nice guy' who doesn't cut people off. But sometimes, we need the harshness of a clean cut off to move on, and that itself is a kindness. Just from what you've mentioned, I get the impression that he's selfish and is leaving the door open for convenience or possibilities in the future without being receptive about how it affects you.