Have some compassion for the guy. I've done what he did too. So have many others. I understand this completely:
Sometimes when you are in so much pain from your oneitis the only sensible way to continue seems to be just closing any possible door for reconciliation. This means telling her, upfront, that you want to move on from her. I know it seems stupid (and it is, ultimately), but I understand where this sentiment comes from. I've done it before.
This may be true. This may not be true. But in the end, WHO CARES. So you gave some girl an ego boost and she thinks she played you - yet by the time any of us get married our previous oneitis girls should be 100% irrelevant.