Yes, I would be pretty annoyed that you let me waste my time, money and emotion getting set up for the 14th and then a few days later dumped me. Would make it much harder to get over to think that you were just 'playing along' for my sake.
If anything it would surley be harder to dump him if he buys you something REALLY nice, as you would surley feel guilty. You may also look a bit like you were after all you could get before you dumped him.